By Sandra Lilley, NBC Latino

CHARLOTTE, N.C. – For the first time in the Democratic party’s history, and in a sign of Latinos’ growing significance as a key voting block, San Antonio Texas Mayor Julian Castro was the first Hispanic to deliver the keynote speech at the Democratic National Convention in Charlotte. Castro, the son of a Latina community activist and an increasingly visible young Latino Democrat, had one overarching message to his speech — America is the land of opportunity, as long as it is a collective priority.

“Of all the fictions we heard last week in Tampa, the one I find most troubling is this: If we all go our own way, our nation will be stronger for it,” said Castro, adding, “because if we sever the threads that connect us, the only people who will go far are those who are already ahead. We all understand that freedom isn’t free — neither is opportunity. We have to invest in it,” said Castro.

The 37-year-old Mayor of San Antonio spoke lovingly of his grandmother, who left Mexico as a little girl, never made it past the fourth grade, worked as a maid, cook and babysitter, and later in life taught herself to read and write in Spanish and English. Castro said only in America would the grandsons of this woman would end up as Mayor (himself) and the other on his way to the U.S. Congress (his twin brother Joaquin). In fact, it was his twin brother Joaquin who introduced Julian, a powerful image of two young Latino politicians who were raised in modest circumstances and are now in the national spotlight.

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“The dream of raising a family in a place where hard work is rewarded is not unique to Americans,” said Castro. “The dream is universal, but America makes it possible, and our investment in opportunity makes it a reality — America didn’t become the land of opportunity by accident,” said Castro. Castro then gave a vigorous defense of Obama’s policies, saying Obama saved a million jobs by rescuing the auto industry, made a historic investment in public schools, and expanded college opportunities through Pell grants. Castro also said Obama succeeded where seven other American Presidents had not, in passing health care legislation.

Then Castro praised Obama for taking action on the Dreamers. “And because he knows we don’t have an ounce of talent to waste, the President took action to lift the shadow of deportation from a generation of young, law-abiding immigrants called dreamers.” He then urged Congress to “enshrine into law their right to pursue their dreams in the only place they’ve ever called home: America,” bringing cheers from the crowd.

Castro’s speech then went on offense against the Republican presidential candidate. “Mitt Romney, quite simply, doesn’t get it,” said Castro. Criticizing Romney for telling students to “borrow money from your parents,” and saying to laughter, “Gee, why didn’t I think of that?” Castro said, “I don’t think Governor Romney meant any harm.  I think he is a good guy.  I just don’t think he has any idea how good he’s had it.”

Castro then added, “The Romney-Ryan budget doesn’t just pummel the middle class — it dismantles it.”  He then said Romney says “no” to getting the middle class back to work, respecting women’s rights, “letting people marry whomever they love,” and expanding access to good health care . He also accused him of undergoing an “extreme makeover” on issues.

Castro  then ended his historic keynote speech on a note that touched on his immigrant grandmother’s journey.

“In the end, the American dream is not a sprint or even a marathon, but a relay…My mother fought hard for civil rights so that instead of a mop, I could hold this microphone,” said Castro, urging the re-election of Barack Obama to build on “shared prosperity.”  Castro’s speech was well received on the convention floor, eliciting enthusiasm and cheers of “four more years.”

Opinion: Castro should act like he belongs

After Castro, First Lady Michelle Obama gave a heartfelt speech in defense of her husband.

“After so many struggles and triumphs and moments that have tested my husband in ways I never could have imagined, I have seen firsthand that being president doesn’t change who you are — it reveals who you are,” said the First Lady to rousing applause. “But at the end of the day, all you have to guide you are your values — so when it comes to rebuilding our economy, Barack is thinking about folks like my dad and like his grandmother,” said Michelle Obama, who talked of her father’s struggles with multiple sclerosis, his pride at paying part of her college tuition, and Barack’s childhood as the son of a single mother who spent much time with his grandparents.

And in a pointed remark aimed at Republican comments that Obama has pitted classes against each other, the First Lady said “our families didn’t begrudge anyone else’s success or care that others had much more than they did — in fact, they admired it.”

Michelle Obama then passionately defended her husband’s record, saying he tackled health care reform, signed the Lily Ledbetter act,  and kept student loans from increasing, because for Obama, “these issues aren’t political — they’re personal.”  Saying he reads letters from Americans late into the night, she says, “I see how those stories … that’s what drives Barack Obama every single day.”

The First Lady also said, “If immigrants could leave behind everything they knew for a better life on our shores, then surely we can give everyone in this country a fair chance at the American Dream.”  She then said, “we must once again come together and stand together for the man we can trust to keep moving this great country forward,” her husband, Barack Obama.

Castro’s and Michelle Obama’s speeches definitely roused the convention floor, and Democrats hope the energy and enthusiasm continue in the next two nights of the convention.

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CHARLOTTE, N.C. – First lady Michelle Obama said her husband remains anchored by the same values he brought to the White House nearly four years ago, on a night devoted as much to tearing down Republican nominee Mitt Romney, as building up President Barack Obama and his record.

Democrats’ message on Tuesday, the first day of the Democratic National Convention, was two-pronged and crystal clear. The evening’s speeches both sought to extol the president’s accomplishments and cast him as empathetic, while at the same time looking to deconstruct Romney and cast him as an impossibly worse choice for president.

Slideshow: The Democratic National Convention

The evening’s top-billed speakers embodied the dual purposes of Tuesday’s programming.  Michelle Obama said her husband was the “same man” he was before the White House, in a speech designed to put a softer edge on the  president’s case for re-election. And keynote speaker Julian Castro said Romney would diminish opportunities for voters if elected, in a speech that also weaved in the personal story of the San Antonio mayor, whom party leaders regard as a rising star.

Justin Sullivan / Getty Images

First lady Michelle Obama speaks on stage during day one of the Democratic National Convention at Time Warner Cable Arena on September 4, 2012 in Charlotte, North Carolina.

VIDEO: Tuesday night's DNC speeches

"I have seen firsthand that being president doesn’t change who you are – no, it reveals who you are," Michelle Obama said in her prime-time speech. "So in the end, for Barack, these issues aren’t political – they’re personal. Because Barack knows what it means when a family struggles ... Barack knows the American Dream because he's lived it."

And the first lady brought the crowd to their feet in closing: "I know from experience that if I truly want to leave a better world for my daughters, and all our sons and daughters ... then we must work like never before, and we must once again come together and stand together for the man we can trust to keep moving this great country forward…my husband, our president, President Barack Obama."

Mrs. Obama's speech capped hours’ worth of speeches in Charlotte, but stood in contrast against most of the day’s earlier speakers, many of whom offered sharp criticism of Romney. So strong were the attacks on the Republican nominee, that it seemed as though many of the efforts to build up Obama were secondary to disparaging Romney.

PhotoBlog: See a 360-degree view of Michelle Obama speaking at the DNC

A spokeswoman for the GOP presidential nominee, Andrea Saul, said late Tueseday evening in response: "On the first night of President Obama’s convention, not a single speaker uttered the words ‘Americans are better off than they were four years ago.’ Instead, there was a night full of tributes to government as the solution to every problem, even going as far as to say that ‘government is the only thing that we all belong to."

Though much of his speech focused on overcoming the difficulties associated with being a poor Latino in Texas as a child, the middle of Castro’s speech took aim at Romney in a way that was similar to those addresses.

"Republicans tell us that if the most prosperous among us do even better, that somehow the rest of us will too. Folks, we’ve heard that before. First they called it 'trickle-down.' Then they called it 'supply-side.' Now it’s 'Romney-Ryan.' Or is it 'Ryan-Romney'?" Castro said. "Either way, their theory's been tested. It failed. Our economy failed. The middle class paid the price. Your family paid the price. Mitt Romney just doesn’t get it.”

As if to clarify the evening's theme, Maryland Gov. Martin O'Malley said: "We understand that progress is a choice. Job creation is a choice. Whether we move forward or back, this too is a choice. And that is what this election is all about."

Other attacks on Romney sought to exploit Obama’s current advantages over his Republican opponents among women and Latinos, two crucial voting blocs which could sway the outcome of the election.

Texas Rep. Charlie Gonzalez, the chairman of the Congressional Hispanic Caucus, said Romney had “embraced the racial profiling policies of Arizona Gov. Jan Brewer and Sheriff Joe Arpaio” by way of praising Arizona’s controversial immigration law as a “model.”

And Senate Majority Leader Harry Reid, D-Nev., who has clashed publicly with the Bain Capital co-founder by contending that there were years in which Romney paid no taxes, excoriated the GOP nominee as opaque and undeserving of trust.

(Reid's charge prompted a response from Romney spokesman Ryan Williams: "Harry Reid has once again shown that he is completely detached from reality. Senator Reid’s comments tonight are absolutely false and are another attempt to distract from President Obama’s abysmal economic record.")

Slideshow: Democratic National Convention

David Goldman / AP

Democrats gather in Charlotte, N.C., to officially nominate President Barack Obama and Vice President Joe Biden as the party's candidates for the 2012 presidential election.

Launch slideshow

The tone of the first night of the Democratic convention seemed more aggressively negative toward Romney than much of the Republican-led criticism of Obama last week in Tampa. It was an emphasis in keeping with Democrats’ effort to turn the election into a choice – in which they try to make Romney seem like a worse pick than Romney – rather than a referendum on Obama’s record after almost four years in office.

The first day of the Democratic convention was also an exercise in energizing the party’s core constituencies. Among the speakers on Tuesday were the leaders of the AFL-CIO and SEIU, two of the nation’s largest labor groups, the president of the pro-abortion rights group NARAL, and speakers like openly gay Colorado Rep. Jared Polis, who praised Obama’s actions to expand gay rights.

Those strides toward building up Obama were certainly part of the programming on Tuesday night, and the achievements most frequently emphasized included the president’s signature health care overhaul law and the bailout of the auto industry in particular.

“Facts are facts: No president since Franklin Delano Roosevelt in the Great Depression inherited a worse economy, bigger job losses or deeper problems from his predecessor,” said O’Malley, the first prime-time speaker of the evening. “But President Obama is moving America forward, not back.”

On Wednesday, Democrats will formally name Obama their candidate re-election after a highly-anticipated nominating speech by former President Bill Clinton.

Obama himself will travel to Charlotte on Wednesday, joining Vice President Joe Biden who made it to the convention city this afternoon. Both men will speak outdoors on Thursday at Charlotte’s Bank of America stadium, the home of the NFL’s Carolina Panthers and a potentially raucous atmosphere the president’s campaign hopes will recapture the imagery of Obama’s 2008 outdoor acceptance speech in Denver.

San Antonio Mayor Julian Castro will go after the Republican presidential ticket for its economic philosophy and try to paint the pair as out of touch.

"Republicans tell us that if the most prosperous among us do even better, that somehow the rest of us will too,” Castro, 37, will say, according to excerpts released by the Democratic National Convention Committee. “Folks...we've heard that before. First they called it 'trickle-down.' Then 'supply side.' Now it's 'Romney/Ryan.' Or is it 'Ryan/Romney'? Either way, their theory has been tested. It failed. Our economy failed. The middle class paid the price. Your family paid the price. Mitt Romney just doesn't get it."

He will note the value of hard work, but add that the country needs to “invest” and help people along the way. 

"Texas may be the one place where people actually still have bootstraps,” he will say, “and we expect folks to pull themselves up by them. But we also recognize there are some things we can't do alone.”

He will add: "Mitt Romney, quite simply, doesn't get it. A few months ago he visited a university in Ohio and gave the students there a little entrepreneurial advice. 'Start a business,' he said. But how? 'Borrow money if you have to from your parents,' he told them. Gee -- why didn't I think of that?" 

The Social Media Story of DNC 2012

He will also lavish praise on President Obama. 

"Now, like many of you, I watched last week's Republican Convention,” he will say. “They told a few stories of individual success...we all celebrate individual success. But the question is, how do we multiply that success. The answer is President Barack Obama."

He adds: "Four years ago, America stood on the brink of a Depression. Despite incredible odds and united Republican opposition, our President took action. And now we've seen 4.5 million new jobs. He knows better than anyone that there's more hard work to do. But we're making progress. And now we need to make a choice. It's a choice...between a country where the middle class pays more, so that millionaires can pay less... or a country where everybody pays their fair share. It's a choice between a nation that slashes funding for our schools and guts Pell grants... Or a nation that invests more in education. It's a choice between a politician who rewards companies that ship American jobs overseas...Or a leader who brings jobs back home.

"This is the choice before us. And to me, to my generation, and for all the generations that will come after us, our choice is clear. Our choice is a man who's always chosen us. A man who already is our President -- Barack Obama."

For more, read: "Who is Julian Castro and can he deliver in the spotlight?"

*** UPDATE *** Ryan Williams, of the Romney campaign, responded this way: “Middle class families understand that they are not better off than they were four years ago because President Obama’s liberal policies have failed to turn around the economy. The president has wasted hundreds of billions of dollars on a big government agenda that has resulted in record debt, declining salaries and 42 consecutive months of unemployment above 8%. Mitt Romney and Paul Ryan have a plan that will strengthen the middle class by reforming our tax code, reducing excessive government regulations and creating 12 million jobs over the next four years.”