Vice President Joe Biden has barely hidden his possible interest in running for president in 2016, and now, the loquacious former senator has begun to lay the groundwork for a potential campaign to succeed President Barack Obama.

"In a couple years, I think he's going to take a hard look at it," Beau Biden, the vice president's son and the attorney general of Delaware, said on MSNBC. "I hope he does."

A potential Biden bid for the presidency will come as little surprise to observers of the vice president over the past few years; Biden has often dropped hints of his interest in running as Democrats' nominee in 2016, and has repeatedly refused to rule out running in 2016 when asked.

Biden further stoked speculation this inaugural weekend, when he stopped by the Iowa State Society's inaugural ball, and invited top New Hampshire Democrats to his formal swearing-in ceremony on Sunday. Both Iowa and New Hampshire traditionally host the first two nominating contests of a presidential cycle.

At the Iowa ball, he mistakenly referred to himself as president, before correcting himself. “I’m proud to be president of the United States,” he said before pausing to rephrase. “I’m proud to be vice president of the United States but I am prouder to be Barack Obama, President Barack Obama’s vice president.”

And on Monday, during the inaugural parade, he glad-handed his way down Pennsylvania Avenue. Biden waved and pointed at parade-goers on the sidelines, and even ran over to shake the hand of NBC’s Al Roker, positioned behind a security barricade.

When he ran into a Republican voter in Florida during the closing days of the campaign, Biden cautioned the Obama administration's health reform law would be a chit in his column during the next presidential campaign. "After it's all over when your insurance rates go down, then you'll vote for me in 2016," he said, employing a quip that quickly drew attention for its electoral implications.

Biden has twice run for president before, in 1988 and 2008. And each time, his candidacy flamed out. In the '88 campaign, Biden withdrew before the first nominating contest following allegations that he had plagiarized portions of speeches.

Biden survived through the Iowa caucus in 2008, but ended his campaign following a fifth place finish in the contest. The then-Delaware senator committed some trademark gaffes during that campaign, too. Biden joked, for instance, about how "you cannot go to a 7-Eleven or a Dunkin' Donuts unless you have a slight Indian accent." He also memorably referred to Obama, his future boss, as "the first mainstream African-American who is articulate and bright and clean."

But Biden, who served in the Senate from 1973 to 2009 and established himself as an expert on matters of foreign policy, now finds himself arguably at the apex of his political strength. Forty-one percent of Americans said they have a positive impression of the vice president in the most recent NBC News-Wall Street Journal poll, versus 37 percent who have a negative impression of Biden. Those aren't blockbuster numbers, but they're among Biden's best in the history of the poll.

But a successful run in 2016 would make Biden the nation’s oldest inaugurated president.  He turns 74 in 2016, a year older than Ronald Reagan when he took the oath at his second inaugural.

Biden emerged during the 2012 Obama campaign as a key asset of the president's, stumping repeatedly in key blue collar corners of swing states like Ohio and Wisconsin. During those stops, the vice president offered some of the sharpest criticism of Republican nominee Mitt Romney's policies in a direct appeal to middle class voters.

Brian Snyder / Reuters

Vice President Joe Biden and his wife, Dr. Jill Biden, dance at the Commander-in-Chief's Ball in Washington, Jan. 21, 2013.

Biden acted as a key player during the president's first term on matters ranging from foreign policy to domestic. Biden was tasked with implementing the 2009 economic stimulus, and Obama asked him more recently to lead the task force that developed recommendations to curb instances of gun violence.

Obama has also repeatedly turned to Biden to lean on his long-standing relationships in the Senate to help forge deals with Republicans. When talks to avert the "fiscal cliff" reached an impasse late this past December, Senate Minority Leader Mitch McConnell, R-Ky., reached out to Biden, who won some of the credit for the last-minute deal.

Still, Biden has also become a favorite target of conservatives during the last four years, not least of which because of his not-infrequent gaffes. Conservative media outlets enjoyed stoking speculation, for instance, that Obama might bump Biden off of the ticket in favor of Secretary of State Hillary Rodham Clinton -- suggesting that Biden had become too big of a liability to the president's re-election campaign.

And indeed, there were moments during the 2012 campaign where Biden veered badly off script. When he expressed his personal support for same-sex marriage during a May 6 appearance on NBC's "Meet the Press," he preempted Obama's own anticipated endorsement of gay and lesbian marriage rights. Obama was forced to hastily follow in the footsteps of his vice president.

Biden also won the enmity of the Romney campaign when he told a predominantly African-American audience that the GOP ticket's economic policies would "put y'all back in chains."

But despite Biden's propensity to fall off-message on occasion, he still enjoys a champion in one key ally: Obama.

"One decision I know was absolutely correct -- absolutely spot on -- was my choice of vice president," Obama said Sunday at an inaugural reception. "I could not have a better partner than Joe Biden."

That's a line that Biden would no doubt love to feature in a campaign ad in just a few years. He might not be the only Democrat in the race -- many in the party hope that Clinton will seek the nomination again -- though the vice president's door to running is open than ever.

To a greater extent than he did in his first inaugural address four years ago, in his speech Monday President Barack Obama made a point of focusing attention on issues vital to specific constituencies within his winning coalition.

Obama’s inaugural theme four years ago was the need for national unity and his call for “a new era of responsibility, a recognition on the part of every American that we have duties to ourselves, our Nation, and the world.” And in his address Monday, Obama again included calls for unity, or what he called “collective action.”

But he went beyond that by, for the first time in a presidential inaugural address, referring explicitly to gay rights and to an event in gay rights history, the 1969 riot outside the Stonewall Inn, a gay bar in Greenwich Village in New York City. The Stonewall Inn protests followed a police raid on the bar and helped launch the gay rights movement.

Related: Obama takes ceremonial oath, tells nation 'our journey is not complete'

Jim Bourg / Reuters

President Barack Obama speaks during swearing-in ceremonies on the West front of the Capitol in Washington, Jan. 21, 2013.

In a statement issued after Obama’s victory last November, the Human Rights Campaign, the leading gay rights advocacy group, said, “HRC and our energized supporters have raised or contributed more than $20 million to re-elect President Obama and to advance marriage equality and other electoral priorities this (2012) cycle.”

In his address, Obama called for states to give legal recognition to marriage by same-sex couples: “Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law – for if we are truly created equal, then surely the love we commit to one another must be equal as well,” he said.

Slideshow: 57th Presidential Inauguration

The major action on this issue will not come from Obama or Congress but from the Supreme Court, which on March 26, 2013 will hear oral arguments in two cases that will decide whether a state can define marriage as the union of one man and one woman. Also, the high court will decide whether a section of the 1996 Defense of Marriage Act, which defines marriage as solely between one man and one woman, violates the constitutional rights of same-sex couples.

Obama linked the Stonewall protests to the 1848 women’s rights convention in Seneca Falls, N.Y., and the 1965 voting rights march in Selma, Ala.

“We, the people, declare today that the most evident of truths – that all of us are created equal – is the star that guides us still; just as it guided our forebears through Seneca Falls, and Selma, and Stonewall … .”

Obama also acknowledged issues important to feminists, to people barred from voting by voter identification laws, and to immigrants illegally present in the United States who hope Congress this year will pass a law creating a process allowing them to become legal residents.

Calling for equal pay for men and women, he said, “Our journey is not complete until our wives, our mothers, and daughters can earn a living equal to their efforts.”

On voting rights, he said, “Our journey is not complete until no citizen is forced to wait for hours to exercise the right to vote.”

And on immigration, Obama said that he and Congress must “find a better way to welcome the striving, hopeful immigrants who still see America as a land of opportunity” and change the law so that “bright young students and engineers are enlisted in our workforce rather than expelled from our country.”

Referencing what’s likely to be a major legislative battle of the next several months, Obama alluded to his call for greater restrictions on the purchase of guns in the aftermath of the Dec. 14 shooting at Sandy Hook Elementary School, saying, “Our journey is not complete until all our children, from the streets of Detroit to the hills of Appalachia to the quiet lanes of Newtown, know that they are cared for, and cherished, and always safe from harm.”

Recommended: Obama's second term begins

Earlier in the address he reiterated a theme from his 2009 inaugural address, urging Congress to take steps to remedy the effects of catastrophic weather events and global climate change.

“We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations,” he said. “Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires, and crippling drought, and more powerful storms.”

Applauding this part of the speech, Frances Beinecke, president of the Natural Resources Defense Council, said, “This is a call to action against the climate chaos that is sweeping our nation and threatening our future. Now it's time to act. Power plants are our single largest source of carbon pollution. We must cut that pollution.”

The crucial arena for action on this issue may not be Congress but the Environmental Protection Agency. While the House did pass cap-and-trade carbon emissions legislation when the Democrats had the majority in 2009, the prospects for such legislation now seem doubtful at best. The Republican-led House is likely to keep a skeptical eye on additional subsidies for alternative energy technologies, although Congress did enact an extension of the Production Tax Credit for wind and other renewable electricity projects as part of the tax bill Obama signed into law on Jan. 2.

Mark Wilson / Getty Images

President Barack Obama is sworn in by Supreme Court Chief Justice John Roberts as First lady Michelle Obama and daughters, Sasha Obama and Malia Obama look on during the public ceremonial inauguration on the West Front of the U.S. Capitol on Jan. 21, 2013.

Updated 4:33 p.m. — President Barack Obama issued a call to unity in his second inaugural address, urging the nation to move past the divisions that marked the last four years in politics and complete the work of living up to America's founding principles.

The president, in a speech that blended together post-partisan rhetoric and policy declarations, highlighted the progress made during his first term to end foreign wars and turn around the economy.

But Obama said that there was much unfinished work ahead, and he used Monday's speech to urge political leaders to finally rise above bitter squabbling — a recurring theme of his first term, and a mark of how difficult it has been for Obama to live up to his 2008 vow to change Washington's business as usual.

"Our journey is not complete," Obama said during one refrain in his speech.

Related: The full text of President Barack Obama's inaugural address

"We cannot mistake absolutism for principle, or substitute spectacle for politics, or treat name-calling as reasoned debate," Obama said. "We must act, knowing that our work will be imperfect.  We must act, knowing that today’s victories will be only partial, and that it will be up to those who stand here in four years, and forty years, and four hundred years hence to advance the timeless spirit once conferred to us in a spare Philadelphia hall."

Obama and Vice President Joe Biden were sworn in by Chief Justice John Roberts and Supreme Court Associate Justice Sonia Sotomayor, respectively, shortly before noon; Monday's oath of office was ceremonial, following their formal, constitutionally-prescribed swearing-in on Sunday.

Monday's ceremonies coincided with the federal holiday honoring Martin Luther King, Jr. Obama nodded to the slain civil rights leader during his speech, and the nation's first African-American president used one of King's Bibles during today's inauguration.

The president's speech, though, strode between acknowledging the accomplishments of his first term and the new priorities for his second. The president begins his new term this week intent upon pursuing an ambitious agenda following his decisive re-election victory last November over Republican opponent Mitt Romney.

Related: First Thoughts: Obama's second term begins

Rebuilding the economy, strengthening entitlement programs for future generations and addressing the threat of climate change were among the initiatives upon which the president touched during his speech. Obama nodded toward other priorities, that were set to define his next four years in office: equal rights for gay and lesbian Americans, immigration reform that offers undocumented residents a pathway to citizenship and new rules to curb gun violence.

But as political leaders from both parties looked on from the inaugural platform, Obama avoided much of the hard-charging rhetoric of last year's campaign.

Romney, the erstwhile GOP nominee, spent Inauguration Day at his home in La Jolla, Calif., and a former aide told NBC News it was unlikely that the former Massachusetts governor would watch today's festivities.

Wisconsin Rep. Paul Ryan, Romney's running mate last fall, said today was not a day to emphasize partisan divisions.

"But today, we put those disagreements aside," Ryan said in a statement. "Today, we remember what we share in common."

To be sure, a variety of bruising political battles between Obama and Congress — in particular, a House of Representatives controlled by Republicans — loomed on the horizon. On Wednesday, Republicans said, they would vote on a measure to extend the nation's debt limit by a few months.

Earlier in the day, Obama and the first family attended a service at St. John's Episcopal Church — the "Church of the Presidents," as it is sometimes known — just two blocks from the White House.

There, Dr. Luis Leon, the rector of the church, led a series of "prayers for the nation," Washington Cardinal Donald Weurl led a Gospel reading, and an Alexandria, Va., rabbi offered a final blessing. Biden and his wife also attended the service.

Former Presidents Bill Clinton and Jimmy Carter were among the dignitaries in attendance during the oath-of-office ceremonies during late Monday morning. Celebrities including musician Jay-Z and actress Eva Longoria joined government officials on the inaugural platform, and attendees were treated to performances by the Brooklyn Tabernacle Choir, Beyonce, Kelly Clarkson and James Taylor.

Obama retreated to a traditional luncheon on Capitol Hill following the inaugural ceremonies before participating in the parade down Washington's Pennsylvania Avenue.

"I recognize that democracy is not always easy, and I recognize there are profound differences in this room," Obama said in a toast before a bipartisan group of lawmakers, "but I just want to say thank you for your service and I want to thank your families for their service, because regardless of our political persuasions and perspectives, I know that all of us serve because we believe that we can make America for future generations."

Afterward, the president and first lady entered the motorcade from the Capitol and back to the White House, leaving the presidential motorcade at moments to walk for a portion of the trip.

The president and first lady will make their way to glitzy, black-tie inaugural balls later this evening before wrapping the whirlwind day of festivities.

NBC's Peter Alexander contributed to this report.

Vice President Biden, Mr. Chief Justice, Members of the United States Congress, distinguished guests, and fellow citizens: 

Each time we gather to inaugurate a president, we bear witness to the enduring strength of our Constitution.  We affirm the promise of our democracy.  We recall that what binds this nation together is not the colors of our skin or the tenets of our faith or the origins of our names.  What makes us exceptional - what makes us American - is our allegiance to an idea, articulated in a declaration made more than two centuries ago:

"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable rights, that among these are Life, Liberty, and the pursuit of Happiness." 

Today we continue a never-ending journey, to bridge the meaning of those words with the realities of our time.  For history tells us that while these truths may be self-evident, they have never been self-executing; that while freedom is a gift from God, it must be secured by His people here on Earth.  The patriots of 1776 did not fight to replace the tyranny of a king with the privileges of a few or the rule of a mob.  They gave to us a Republic, a government of, and by, and for the people, entrusting each generation to keep safe our founding creed. 

For more than two hundred years, we have. 

Through blood drawn by lash and blood drawn by sword, we learned that no union founded on the principles of liberty and equality could survive half-slave and half-free.  We made ourselves anew, and vowed to move forward together. 

Together, we determined that a modern economy requires railroads and highways to speed travel and commerce; schools and colleges to train our workers.

Together, we discovered that a free market only thrives when there are rules to ensure competition and fair play. 

Together, we resolved that a great nation must care for the vulnerable, and protect its people from life's worst hazards and misfortune.

Through it all, we have never relinquished our skepticism of central authority, nor have we succumbed to the fiction that all society's ills can be cured through government alone.  Our celebration of initiative and enterprise; our insistence on hard work and personal responsibility, are constants in our character.

But we have always understood that when times change, so must we; that fidelity to our founding principles requires new responses to new challenges; that preserving our individual freedoms ultimately requires collective action.  For the American people can no more meet the demands of today's world by acting alone than American soldiers could have met the forces of fascism or communism with muskets and militias.  No single person can train all the math and science teachers we'll need to equip our children for the future, or build the roads and networks and research labs that will bring new jobs and businesses to our shores.  Now, more than ever, we must do these things together, as one nation, and one people. 

This generation of Americans has been tested by crises that steeled our resolve and proved our resilience.  A decade of war is now ending.  An economic recovery has begun.  America's possibilities are limitless, for we possess all the qualities that this world without boundaries demands:  youth and drive; diversity and openness; an endless capacity for risk and a gift for reinvention.   My fellow Americans, we are made for this moment, and we will seize it - so long as we seize it together. 

For we, the people, understand that our country cannot succeed when a shrinking few do very well and a growing many barely make it.  We believe that America's prosperity must rest upon the broad shoulders of a rising middle class.  We know that America thrives when every person can find independence and pride in their work; when the wages of honest labor liberate families from the brink of hardship.  We are true to our creed when a little girl born into the bleakest poverty knows that she has the same chance to succeed as anybody else, because she is an American, she is free, and she is equal, not just in the eyes of God but also in our own. 

We understand that outworn programs are inadequate to the needs of our time.  We must harness new ideas and technology to remake our government, revamp our tax code, reform our schools, and empower our citizens with the skills they need to work harder, learn more, and reach higher.  But while the means will change, our purpose endures:  a nation that rewards the effort and determination of every single American.  That is what this moment requires.  That is what will give real meaning to our creed.  

We, the people, still believe that every citizen deserves a basic measure of security and dignity.  We must make the hard choices to reduce the cost of health care and the size of our deficit.  But we reject the belief that America must choose between caring for the generation that built this country and investing in the generation that will build its future.  For we remember the lessons of our past, when twilight years were spent in poverty, and parents of a child with a disability had nowhere to turn.  We do not believe that in this country, freedom is reserved for the lucky, or happiness for the few.  We recognize that no matter how responsibly we live our lives, any one of us, at any time, may face a job loss, or a sudden illness, or a home swept away in a terrible storm. The commitments we make to each other - through Medicare, and Medicaid, and Social Security - these things do not sap our initiative; they strengthen us.  They do not make us a nation of takers; they free us to take the risks that make this country great. 

We, the people, still believe that our obligations as Americans are not just to ourselves, but to all posterity.  We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations.  Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires, and crippling drought, and more powerful storms.  The path towards sustainable energy sources will be long and sometimes difficult.  But America cannot resist this transition; we must lead it.  We cannot cede to other nations the technology that will power new jobs and new industries - we must claim its promise.  That is how we will maintain our economic vitality and our national treasure - our forests and waterways; our croplands and snowcapped peaks.  That is how we will preserve our planet, commanded to our care by God.  That's what will lend meaning to the creed our fathers once declared.

We, the people, still believe that enduring security and lasting peace do not require perpetual war.  Our brave men and women in uniform, tempered by the flames of battle, are unmatched in skill and courage.  Our citizens, seared by the memory of those we have lost, know too well the price that is paid for liberty.  The knowledge of their sacrifice will keep us forever vigilant against those who would do us harm.  But we are also heirs to those who won the peace and not just the war, who turned sworn enemies into the surest of friends, and we must carry those lessons into this time as well.

We will defend our people and uphold our values through strength of arms and rule of law.  We will show the courage to try and resolve our differences with other nations peacefully - not because we are naïve about the dangers we face, but because engagement can more durably lift suspicion and fear.  America will remain the anchor of strong alliances in every corner of the globe; and we will renew those institutions that extend our capacity to manage crisis abroad, for no one has a greater stake in a peaceful world than its most powerful nation.  We will support democracy from Asia to Africa; from the Americas to the Middle East, because our interests and our conscience compel us to act on behalf of those who long for freedom.  And we must be a source of hope to the poor, the sick, the marginalized, the victims of prejudice - not out of mere charity, but because peace in our time requires the constant advance of those principles that our common creed describes:  tolerance and opportunity; human dignity and justice. 

We, the people, declare today that the most evident of truths - that all of us are created equal - is the star that guides us still; just as it guided our forebears through Seneca Falls, and Selma, and Stonewall; just as it guided all those men and women, sung and unsung, who left footprints along this great Mall, to hear a preacher say that we cannot walk alone; to hear a King proclaim that our individual freedom is inextricably bound to the freedom of every soul on Earth. 

It is now our generation's task to carry on what those pioneers began.  For our journey is not complete until our wives, our mothers, and daughters can earn a living equal to their efforts.  Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law - for if we are truly created equal, then surely the love we commit to one another must be equal as well.  Our journey is not complete until no citizen is forced to wait for hours to exercise the right to vote.  Our journey is not complete until we find a better way to welcome the striving, hopeful immigrants who still see America as a land of opportunity; until bright young students and engineers are enlisted in our workforce rather than expelled from our country.  Our journey is not complete until all our children, from the streets of Detroit to the hills of Appalachia to the quiet lanes of Newtown, know that they are cared for, and cherished, and always safe from harm. 

That is our generation's task - to make these words, these rights, these values - of Life, and Liberty, and the Pursuit of Happiness - real for every American.  Being true to our founding documents does not require us to agree on every contour of life; it does not mean we will all define liberty in exactly the same way, or follow the same precise path to happiness.  Progress does not compel us to settle centuries-long debates about the role of government for all time - but it does require us to act in our time. 

For now decisions are upon us, and we cannot afford delay.  We cannot mistake absolutism for principle, or substitute spectacle for politics, or treat name-calling as reasoned debate.  We must act, knowing that our work will be imperfect.  We must act, knowing that today's victories will be only partial, and that it will be up to those who stand here in four years, and forty years, and four hundred years hence to advance the timeless spirit once conferred to us in a spare Philadelphia hall.

My fellow Americans, the oath I have sworn before you today, like the one recited by others who serve in this Capitol, was an oath to God and country, not party or faction - and we must faithfully execute that pledge during the duration of our service.  But the words I spoke today are not so different from the oath that is taken each time a soldier signs up for duty, or an immigrant realizes her dream.  My oath is not so different from the pledge we all make to the flag that waves above and that fills our hearts with pride. 

They are the words of citizens, and they represent our greatest hope. 

You and I, as citizens, have the power to set this country's course. 

You and I, as citizens, have the obligation to shape the debates of our time - not only with the votes we cast, but with the voices we lift in defense of our most ancient values and enduring ideals. 

Let each of us now embrace, with solemn duty and awesome joy, what is our lasting birthright.  With common effort and common purpose, with passion and dedication, let us answer the call of history, and carry into an uncertain future that precious light of freedom. 

Thank you, God Bless you, and may He forever bless these United States of America.

Slideshow: Obama's first term

Robin Buckson / AP

The president's first four years at the White House in pictures.

Launch slideshow

Just 11 weeks removed from a sweeping re-election victory, President Barack Obama has hit the ground running with an ambitious second-term agenda that includes tackling the mounting national debt, immigration and gun control.

But the window in which the president has any hopes of meeting his aggressive goals has already begun to close.

Confronting the fading effectiveness of a second-term presidency, dogged opposition from Republicans in Congress and unexpected hurdles that will inevitably arise over the next four years, Obama must act with a sense of urgency on his plans, particularly amid the fiscal cliff negotiations.

“Second-term presidents generally get eight months or so ... where there's a honeymoon to push an agenda,” said James Thurber, the director of Center for Congressional and Presidential Studies at American University. “He doesn't even have a month.”

Newly armed with “Organizing for Action” – the remnants of the president’s campaign structure, converted to a nonprofit for advocacy purposes – Obama has suggested he will indeed act quickly on his top priorities.

But the next few months might well test the limits of the political capital that the president won in November, which saw Obama score a decisive victory over Republican opponent Mitt Romney and Democrats add seats in the House and the Senate.

If this past December’s lame duck Congress – in which Obama won higher tax rates for the wealthy, but only after a bitter fight with Republicans – offers any lessons, it’s that the GOP is equally committed to pursuing its own priorities, making compromise just as elusive as before.

The fiscal cliff fight will extend into this spring, when the government hits a series of major deadlines to keep the government funded and prevent a default on the national debt. That bare-knuckled fight could make or break Obama’s hopes of accomplishing much else on his agenda.

“I don't believe that he can wait until the last minute to deal with the debt ceiling and sequestration,” said Martin Frost, a former Democratic congressman from Texas. “That's got to be worked out during February.”

That fight would threaten to consume much of the political oxygen in Washington in any normal year. And Obama’s ability to pivot toward his other major priorities, gun violence and immigration, may well hinge upon how quickly and cleanly he can dispense with this spring’s spending fight.

History suggests that many presidents cannot hope to accomplish much in the last two years of their term, when the jockeying for the next presidential campaign begins. And with midterm elections looming in 2014, lawmakers will inevitably turn at some point from governing to politicking.

"There's kind of an arc of achievement in presidential administrations. Usually the first few months of a new administration is where most of the accomplishment takes place," said Ross Baker, a presidential historian at Rutgers University. "It's hard to imagine getting another piece of legislation of the magnitude of the Affordable Care Act in the second term."

And Obama’s hopes of significant reforms to immigration and gun laws might well depend upon how well (or how poorly) the spending fight with Congress proceeds.

The president last week laid out a series of measures intended to curb gun violence, most significantly proposals to limit the size of ammunition magazines, ban assault weapons and require universal background checks on firearm purchases. That plan won little praise from Republicans, and Obama might have to lean upon any reservoir of goodwill he has left after the spending fight to reach his goals.

Obama is practically obligated to attempt immigration reform after soothing the Latino community during last year’s election about his inability to follow through with a pledge to accomplish immigration reform in his first term. If re-elected, Obama told Hispanic voters, he would make immigration reform a priority in this second term.

Both proposals could engender significant Republican resistance, a phenomenon familiar to any observers of Obama’s first four years in office.

Another significant – and unpredictable – variable that could ruin even the best-laid plans involves the unknown crises that will inevitably arise during Obama’s second term.

A foreign policy crisis could always erupt and consume the president’s attention. Uprisings in Egypt, Libya and Syria, for instance, proved to major developments during Obama’s first four years in office.

If anything, the president’s first term offered a cautionary tale of how difficult it can be to navigate the obstacles to success that can arise.

The president nearly saw his signature health reform law go down to defeat after the advent of the Tea Party movement, for instance.

And external events – a near-meltdown of the economy, mass shootings, the Gulf of Mexico oil spill and other crises – consumed as much of the president’s first term as anything else.

Just as foreign policy could prove to be a diversion from policy making, it’s one of the few policy areas where a lame-duck president can leave a legacy.

For instance, Bill Clinton, in the waning days of his presidency, concentrated on achieving an elusive peace deal between Israelis and Palestinians.

“He's got a whole range of things on his plate right now,” Frost said of Obama, “it just really depends on how he prioritizes things.”

Drunken rants, flamethrowers, dead canaries and newfangled pants.

No, that's not a summary of deleted scenes from "The Hangover."  It's a list of some of the more interesting highlights from our nation's rich history of past presidential inaugurations.

Besides the pomp and circumstance, the inauguration -- with its associated balls and parades -- is a logistical puzzle, complete with all the potential chaos that comes with organizing a heavily attended event in wintertime, in a swamp of an East Coast city.

Recommended - Inauguration playlist: Jam to Beyonce, Kelly Clarkson and more

From mishaps to glory, here are a few pieces of inaugural trivia you can use to impress your friends and neighbors.

** As vice president, an ill Andrew Johnson became so intoxicated on the day of Lincoln's inauguration that he gave a rambling speech about himself before becoming too confused to perform his duty swearing in the new senators. "The inauguration went off very well except that the Vice President Elect was too drunk to perform his duties & disgraced himself and the Senate by making a drunken foolish speech," wrote Sen. Zachariah Chandler of Michigan at the time.

Slideshow: Inaugural history: From Lincoln to Obama

Abraham Lincoln swore the oath in front of an incomplete Capitol dome. Lyndon B. Johnson became president on Air Force One next to a dazed Jacqueline Kennedy. A collection of photographs from past presidential inaugurations.

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** Good trivia: First president of the United States who was not born a British subject? Martin Van Buren, inaugurated 1837.

** Even better trivia: First president to wear long trousers instead of knee breeches? John Quincy Adams, 1825.

** At the very first inauguration in 1789, the Bible used by President George Washington was hastily opened to Genesis 49:13, which reads, "Zebulun shall dwell at the haven of the sea; and he shall be for an haven of ships; and his border shall be unto Zidon."

** In 2009, President Barack Obama used the Lincoln Bible, used by Abraham Lincoln at his presidential inauguration. The book, published in 1853, has 1,280 pages.

** For John F. Kennedy's inauguration in 1961, a morning snow left an accumulation of about eight inches. Army flame throwers were used to clear it from Pennsylvania Avenue.

** The estimated temperature at Ronald Reagan's first inaugural was a balmy 55 degrees Fahrenheit. At his second, it was a frigid seven -- the coldest inauguration on record -- and the ceremony had to be held inside.

** At another chilly celebration, in 1873, guests at President Ulysses S. Grant's ball had to dance in their coats because the temporary structure built for the occasion was so frigid. Champagne became Slurpee-like in consistency, and the flock of canaries brought in for guests' enjoyment ended up freezing to death.

** After the assassination of Abraham Lincoln, Andrew Johnson was sworn in at his residence at the Kirkwood House on Pennsylvania Avenue. The site is now a high-rise.

** After Kennedy was assassinated, Lyndon Johnson took the oath of office on Air Force One. It was the first time the presidential or vice presidential oath of office was administered by a woman, U.S. District Judge Sarah T. Hughes.

Related: Watching the presidential inauguration with NBC News

** The first televised inaugural ceremony was Harry Truman's in 1949. The first broadcast nationally by radio was Calvin Coolidge's in 1925. The first known photographs from an inauguration were in 1857 at the ceremony for James Buchanan.

** The tradition of inaugural balls is traced to the first one thrown for James and Dolley Madison. Tickets to the 1809 gala, held at Long's Hotel, were $4 apiece. 

** A grand ball for James Buchanan in 1857 included 400 gallons of oysters, 75 hams and $3,000 worth of wine. (That's more than $70,000 in today's money.) 

Sources: Joint Congressional Committee on Inaugural Ceremonies, Senate Historical Office.

Larry Downing / Reuters

President Barack Obama gets a hug from his daughter Malia as wife Michelle and daughter Sasha looks on in the Blue Room of the White House in Washington, Jan. 20, 2013.

President Barack Obama was officially sworn in Sunday for his second term as president of the United States, ahead of Monday's public events.

In a small and succinct ceremony at the White House, Obama recited the constitutionally mandated oath of office for the third of four expected times during his time in office.  

Embracing his children after the oath, his younger daughter Sasha was heard to whisper “good job, Daddy!” 

"I did it!" he responded, before she observed "You didn't mess up." 

Sunday's official swearing-in, administered by Chief Justice John Roberts, was the 57th inauguration of a president in American history. 

Wearing a dark suit and blue tie, Obama repeated the directive to “preserve, protect, and defend the Constitution of the United States." He was joined by First Lady Michelle Obama and his daughters Sasha and Malia.  

After thanking Roberts and waving to cameras, Obama and the first family left the White House's Blue Room. He will deliver his public inaugural address Monday on the west front of the United States Capitol.

During the brief swearing-in Sunday, the first lady -- who wore a dark blue dress -- held the family Bible upon which Obama laid his hand to swear the oath. According to inaugural officials, the Bible was a gift from Mrs. Obama’s father to his mother in 1958.

When Obama first took the oath of office on Jan. 20 four years ago, he and Chief Justice John Roberts tripped up over the wording, raising concerns about whether the constitutional requirements were fulfilled to the letter of the law.  Roberts went to the White House the next day and administered it again in full. 

The short Sunday ceremony was held because the constitutionally mandated inauguration date of Jan. 20 falls on a Sunday, so Obama will take the oath a fourth and final time on Monday before hundreds of thousands of observers on the National Mall. 

The Monday ceremonies will include the president's inaugural address, a luncheon with the president and members  of Congress and the traditional inaugural parade and balls. 

Ahead of the ceremony, the Obama family attended church at the Metropolitan African Methodist Episcopal Church in Washington , a historic place of worship that also hosted pre-inaugural services for former President Bill Clinton and Vice President Albert Gore.

Vice President Joe Biden was officially sworn in at about 8:20 a.m. ET Sunday.

The small weekend ceremonies for both men are a bit of a historical quirk, although today's swearing-in was the seventh in history to take place on a Sunday.  The last instance occurred in 1985, when President Ronald Reagan was formally sworn in for his second term in office.

Beginning with the second inauguration of Franklin D. Roosevelt in 1937, new presidents and vice presidents have been sworn in on Jan. 20 due to the changes laid out in the 20th Amendment to the Constitution.

(Before that, inaugurations were typically held on March 4, as directed by the 12th Amendment. But controversy over the length of the lame duck period forced that ceremony to be moved up by law).

Slideshow:

Jewel Samad / AFP - Getty Images

Festivities for President Barack Obama's second inauguration.

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RELATED: More Inauguration Day content from NBCPolitics.com

In addition, eight vice presidents have been administered the oath of office upon the death of a president. The hastily planned ceremonies have taken place in hotels, homes and -- famously, after the death of John F. Kennedy -- aboard Air Force One. 

The oath of office for the president is set out in the Constitution.

Article II, Section 1, states as follows "Before he enter on the execution of his office, he shall take the following oath or affirmation: -- "I do solemnly swear (or affirm) that I will faithfully execute the office of president of the United States, and will to the best of my ability, preserve, protect, and defend the Constitution of the United States."

Traditionally, two minor changes are made. First, the president taking the oath says his name after the first word ("I, Barack Hussein Obama"). And second, the phrase "so help me God" is added at the end. 

NBC's Pete Williams and Shawna Thomas contributed to this report. 

Joe Biden was sworn in to a second term as the Vice President of the United States on Sunday morning, taking his oath from Associate Justice Sonia Sotomayor -- the first Hispanic in American history to administer an oath of office.

Biden personally selected Sotomayor, who is also the fourth woman to administer an oath, to conduct the brief ceremony at the vice president's residence at the Naval Observatory in Washington, D.C. 

By law, the president and vice president must be sworn in on Jan. 20. Because that date falls on a Sunday this year, both men take their formal oaths today, but will hold the traditional longer public ceremony tomorrow. 

Biden's swearing-in was originally scheduled to be held shortly before the president's, near noon Sunday. But Sotomayor's previous commitment to a book signing in New York City prompted officials to move the event earlier in the day. 

"It's an incredible honor to have Associate Justice Sonia Sotomayor swear me in," Biden said in a statement. "I believed strongly that she would make a great Justice, and it was one of the greatest pleasures of my career to be involved in her selection to the Court.  From the first time I met her, I was impressed by Justice Sotomayor's commitment to justice and opportunity for all Americans, and she continues to exemplify those values today. Above all, I'm happy for the chance to be sworn in by a friend - and someone I know will continue to do great things."

After the short swearing-in, Biden again thanked Sotomayor personally, explaining to the small group of guests the reason for the early timing of the event. 

Biden took the oath on a family Bible bearing a Celtic cross. It has been in the Biden family since 1893.

Cabinet members attending the ceremony included Attorney General Eric Holder and Interior Secretary Ken Salazar. He was joined on stage by his family, including wife Dr. Jill Biden and his three children. 

All inaugural addresses are not created equal, but through the course of the nation’s history, presidents have used the occasion to sketch their visions on topics as old as the republic itself – unity, sacrifice and the proper role of government.

By the time Barack Obama delivered his first inaugural address on Jan. 20, 2009, he had already become famous as an orator with his smashing debut at the 2004 Democratic National Convention and his Iowa caucus victory speech in January 2008.

“There is not a liberal America and conservative America – there is the United States of America,” he declared in the 2004 speech.

A star was born that night and his exhilarating speech on the night he won the Iowa caucuses in 2008 proved to his fans that his rhetorical skill could carry him to the presidency.

He claimed victory in Iowa over those who "said this country was too divided, too disillusioned, to ever come together around a common purpose. But on this January night, at this defining moment in history, you have done what the cynics said we couldn't do.”

By the time Obama stood up to take his oath of office at the Capitol, the improbable had become reality. The “cynics” had long since been vanquished.

Like other presidents in their inaugural addresses, Obama in 2009 faced the familiar tasks of sounding a call for national renewal and proclaiming a faith in ordinary Americans.

As Bill Clinton had said in his first inaugural in 1993, “There is nothing wrong with America that cannot be cured by what is right with America.” Many inaugural speeches – from Thomas Jefferson’s in 1801 to Ronald Reagan’s in 1981 to Obama’s in 2009 -- are elaborations of the upbeat theme that Clinton sounded in 1993.

Since an inauguration – especially a first one – is a fresh start, the newly sworn-in president naturally will proclaim that voters have brought about long-overdue change. “You have changed the face of Congress, the presidency and the political process itself.” That wasn’t Obama speaking in 2009; it was Bill Clinton in his 1993 inaugural address.

Moral improvement
Obama’s first inaugural seems at certain points remarkably personal. In it he did not mention his mother, whom he had often evoked in his 2008 campaign speeches, but he did twice mention his father – whom he never saw after he was 10 years old.

His own life story and the nation’s history were uniquely intertwined, Obama implied, alluding at one point to all the people around the globe watching him taking the oath, including the people in “the small village where my father was born” in Kenya.

He said America’s ability to reform itself was “why a man whose father less than 60 years ago might not have been served at a local restaurant can now stand before you to take a most sacred oath.”

Obama offered a strikingly optimistic view of every nation’s ability to become more like America at its best: capable of moral improvement, tolerant, and committed to unifying and noble ideals, without regard to a person’s ethnicity or skin color.

“Because we have tasted the bitter swill of civil war and segregation and emerged from that dark chapter stronger and more united, we cannot help but believe that the old hatreds shall someday pass; that the lines of tribe shall soon dissolve; that as the world grows smaller, our common humanity shall reveal itself,” he said.

His defeat of John McCain in the November election and of Hillary Clinton and other rivals in the Democratic primaries was a victory of ideals: “We have chosen hope over fear, unity of purpose over conflict and discord.”

Like Clinton in 1993, Obama said that voters had changed the American political system itself: “On this day, we come to proclaim an end to the petty grievances and false promises, the recriminations and worn-out dogmas that for far too long have strangled our politics.”

As for just one of the specific promises Obama made in that speech: “We will wield technology's wonders to raise health care's quality and lower its cost.”

He did sign into law a landmark health care overhaul but whether its provisions will lower the cost of medical care has yet to be determined.

Role of government
Obama used his inaugural to join the long-running debate with small government conservatives – a debate that Clinton had joined in his second inaugural address in 1997.

Slideshow: Inaugural history: From Lincoln to Obama

Abraham Lincoln swore the oath in front of an incomplete Capitol dome. Lyndon B. Johnson became president on Air Force One next to a dazed Jacqueline Kennedy. A collection of photographs from past presidential inaugurations.

Launch slideshow

Reagan had said in 1981, “In this present crisis, government is not the solution to our problem; government is the problem.”

In his 1997 inaugural, Clinton rebutted Reagan, or at least tried to redefine the debate: “We have resolved for our time a great debate over the role of government. Today we can declare: government is not the problem, and government is not the solution. We – the American people – we are the solution.”

Obama, once again assailing unnamed “cynics” as he did in his Iowa speech, said in his inaugural address that his election allowed Americans to move beyond old arguments about the size of the federal government.

“What the cynics fail to understand is that the ground has shifted beneath them; that the stale political arguments that have consumed us for so long no longer apply,” he declared. “The question we ask today is not whether our Government is too big or too small, but whether it works; whether it helps families find jobs at a decent wage, care they can afford, a retirement that is dignified. Where the answer is yes, we intend to move forward. Where the answer is no, programs will end.”

So far, that last promise has not yet been kept: Obama has significantly expanded the federal role in health care but hasn’t yet ended any major federal program.

What makes an inaugural speech one for the history books is a president’s eloquence at a moment of national crisis. Very few inaugural addresses are, like Lincoln’s immortal and remarkably short (701 words) second inaugural, carved in their entirety in granite on the National Mall or anywhere else, but on some rare occasions a president’s words do seem to define an era.

Franklin Roosevelt did that in 1933, at the depth of the gravest economic crisis of modern times, attacking what he called “the unscrupulous money changers” whose practices “stand indicted in the court of public opinion, rejected by the hearts and minds of men.”

He said, “The money changers have fled from their high seats in the temple of our civilization.”

That scalding attack on Wall Street is less well remembered today than FDR’s serene confidence in a dark hour: “This great nation will endure as it has endured, will revive and will prosper. So, first of all, let me assert my firm belief that the only thing we have to fear is fear itself.”

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Former Presidents George W. Bush and George H.W. Bush will not attend the inauguration of President Barack Obama on Monday, a source familiar with inaugural planning confirms.

A spokesman for George H.W. Bush tweeted that the former president and his wife would not attend, the first time he has missed an inaugural since 1997.

Bush, 88, was released Monday from a Houston hospital after seven weeks of treatment for bronchitis, a bacterial infection and a persistent cough.

His son will not attend either. "President and Mrs. Bush wish President Obama and his family all the best for a wonderful inaugural weekend," said spokesman Freddy Ford.

The source confirmed that former Presidents Jimmy Carter and Bill Clinton will attend.