Rick Santorum suspends his 2012 presidential campaign at an event in Gettysburg, Pa.

Updated 3:02 p.m. - Former Pennsylvania Sen. Rick Santorum suspended his campaign on Tuesday, clearing Mitt Romney’s path to the Republican presidential nomination.

Citing weekend reflection with his family, prompted in part by a hospital stay for his youngest daughter, Santorum suspended his campaign, effective today.

"Ladies and gentleman, we made the decision to get into this race at our kitchen table against all the odds," Santorum said in remarks to reporters in Gettysburg, Pa.

"We made a decision over the weekend that while this presidential race for us is over for me and we will suspend our campaign effective today. We are not done fighting."

The announcement effectively stifles opposition to Romney from within the GOP; amid signs that the Republican establishment has started to rally around Romney, the former Massachusetts governor no longer faces any serious conservative challenger.

Former House Speaker Newt Gingrich and Texas Rep. Ron Paul remain active candidates, though neither of them have a plausible path to winning the 1,144 delegates needed to secure the nomination.

The decision comes two weeks before the Pennsylvania presidential primary. Santorum had faced the prospect of an embarrassing loss to Romney that threatened to short-circuit any of his future political aspirations, either statewide or nationally.

Slideshow: Rick Santorum's political life

A look at the Pennsylvania politician — his career on Capitol Hill and his White House aspirations.

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Santorum’s announcement also follows the second health scare of the year for his daughter Bella who suffers from the chromosomal disorder Trisomy 18.

RELATED: What 'suspending' a campaign means

However, the former senator also huddled with conservative supporters recently to mull whether a path forward for his campaign truly existed. As recently as April 3, when he lost the Wisconsin primary to Romney, Santorum vowed to press forward, and described the race for the nomination as only having reached “halftime.”

Still, the course of the primary campaign meant a remarkable political resurrection for Santorum since his landslide defeat in 2006, when he sought a third term in the Senate. His presidential campaign offered a path to political redemption that had been unthinkable, even as recently as the end of last year.

Santorum called Romney earlier today to relay news of his decision.

"Senator Santorum is an able and worthy competitor, and I congratulate him on the campaign he ran. He has proven himself to be an important voice in our party and in the nation," Romney said in a written statement following Tuesday's announcement. "We both recognize that what is most important is putting the failures of the last three years behind us and setting America back on the path to prosperity."

First Read: Santorum's surprising ride

From non-factor to Iowa victor
Santorum was a non-factor in the campaign for most 2011 until a last-minute surge in Iowa, where he had traveled more than any other candidate.

The former Pennsylvania senator had done the first nominating state the “traditional” way, having traveled to all 99 of Iowa’s counties.

Still, a series of candidates – Rep. Michele Bachmann, Texas Gov. Rick Perry, Herman Cain and former House Speaker Newt Gingrich – had taken turns surging to the top of the polls in the Hawkeye State before Santorum got his boost, in late December, on the eve of the state’s caucuses.

Santorum battled Romney to a virtual tie in Iowa before the state’s Republican Party crowned Romney the apparent winner by a slim, eight-vote margin.

It wasn't until Jan. 21 – the day of the South Carolina primary – that the Iowa GOP reversed itself due to unaccounted votes and declared Santorum the actual winner of the caucuses. By then, Romney had steam-rolled his opponents to win the New Hampshire primary, and Gingrich had re-emerged as the leading conservative challenger to Romney in the Palmetto State.

Santorum re-emerged as Romney’s biggest threat on Feb. 7, when he stunned the front-runner by winning contests in Minnesota, Colorado and Missouri.

Santorum as chief Romney alternative
Santorum’s victories in those states again laid bare fissures in the Republican Party over Romney’s candidacy. The most conservative elements of the party appeared unwilling to line up behind Romney. And with Gingrich fading in the aftermath of an onslaught of negative advertising in Florida, Santorum again claimed the mantle of chief Romney alternative. 

The emergence of a supportive super PAC – the Red, White and Blue Fund – helped Santorum make his case. Much of that group’s financing came from investor Foster Friess.

The turning point in the Santorum-Romney battle came in at the end of February.  Rather than skip the primary in Michigan – the state where Romney was raised and where his father had been an iconic Republican governor – Santorum decided to take his battle to Romney’s home turf.

The campaigning turned heavily on issues of class, and Santorum emphasized his commonness with the state’s hard-hit working and middle classes.

He was aided by Democratic-led efforts to remind voters of Romney’s opposition to the 2009 bailouts of General Motors and Chrysler, along with Romney’s own missteps (among them, a highly-touted address to a cavernous Ford Field).

But Santorum also found himself the victim of tough ads launched by Romney and Restore Our Future, the pro-Romney super PAC.

The former senator was also dogged by questions about hot-button social issues, including contraception – a subject that was at the center of an intense national debate over women’s health issues.

Romney eventually eked out a three-point victory of Santorum, but carried momentum from Michigan (and Arizona, where he won a primary the same day) into Super Tuesday’s slate of 10 contests on March 6. There, Romney used the same strategy he had in Michigan to win six of the states, including Ohio, where Santorum had also sought to challenge Romney.

But Santorum was again able to beat back Romney, who gained some separation from his challengers in the delegate count after Super Tuesday, by way of winning Mississippi and Alabama’s primaries. Romney campaigned fleetingly in the states, but the deep conservatism of both states tilted the contests toward Santorum.

The Gingrich factor
Those primaries also made clear, though, that Gingrich’s continued presence in the race had eaten into Santorum’s support among conservatives.

Backers of the former senator started demanding Gingrich’s exit from the race, but the former House speaker defiantly vowed to continue with his campaign through the Republican convention this summer in Tampa.

All the while, Romney continued to amass delegates by winning caucuses and primaries in far-flung U.S. territories.

And it was one U.S. territory, Puerto Rico, where Romney finally trounced Santorum, despite the ex-senator having campaigned there. He subsequently paraded into Illinois, where he won the March 20 primary in the Land of Lincoln.

Romney’s decisive win in Illinois prompted many national party leaders who had remained neutral – former Florida Gov. Jeb Bush, Florida Sen. Marco Rubio and Wisconsin Rep. Paul Ryan, among others – to get off the fence and endorse Romney in hopes of hastening the end of the primary campaign.

Santorum persevered through the April 3 primaries in D.C., Maryland and Wisconsin, then left the campaign trail when his daughter was admitted to the hospital last week.

The ex-senator was reflective in his remarks announcing the suspension of his campaign.

"Miracle after miracle, this race was as improbable as any race you'll ever seen for president," he said, referencing the 11 states and millions of votes won over the course of his campaign. He made no mention of Romney.

Romney still faces token opposition in his march to formalize the nomination. Both Gingrich and Santorum signaled that they would continue – for now – with their campaigns in the aftermath of Santorum's announcement.

"I am committed to staying in this race all the way to Tampa so that the conservative movement has a real choice.  I humbly ask Senator Santorum’s supporters to visit Newt.org to review my conservative record and join us as we bring these values to Tampa," said Gingrich, whose persistence in the race had divided votes with Santorum in some pivotal contests.

Paul's campaign manager said that the Texas congressman would "plan to continue running hard" through the August convention in Tampa.

Susan Walsh / AP

President Barack Obama speaks before the National Governors Association, Monday, Feb. 27, 2012, in the State Dining Room of the White House.

The last time a Democratic presidential candidate won Arizona was 16 years ago, when Bill Clinton carried it in 1996.

The time before that? More than half a century ago, when Harry Truman won the state.

But as Republicans compete in their own primary there today, President Barack Obama's re-election team also has its eye on Arizona, a state where a growing Hispanic electorate and a deep divide on immigration policy could potentially help the president collect a much-needed 11 electoral votes in November.

A win there would be a reach, however. A recent NBC/Marist poll put Obama's approval rating in the state below 40%, and it showed him trailing most of the Republican presidential candidates there.

While Obama -- who didn't contest Arizona four years ago -- lost it by eight percentage points in 2008, his team believes that Sen. John McCain's less-than-double-digit victory in his own home state did much to lay bare Republicans' vulnerability there.

And, four years later, Obama's opponent is likely to face a much harsher reception from the state's growing Latino electorate than McCain, whose push for comprehensive immigration reform nearly derailed his candidacy early in the GOP primary.

From vows to veto the DREAM Act to heavy courtship of controversial endorsers like Arizona's Maricopa County Sheriff Joe Arpaio, GOP candidates' language on immigration has prompted public worry from Republican Hispanic groups as well as from party leaders like former Gov. Jeb Bush.

In Arizona, which became ground zero for the immigration debate after its 2010 passage of legislation that would give police broad authority to detain suspected illegal residents, Democrats have a favorite noun to describe Republican rhetoric on the matter.

"Overreach."

"I can't underscore enough our sense on the ground is that Republicans have overplayed their hand in terms of rhetoric and legislating immigration law," says Phoenix-based Democratic strategist Barry Dill. "And there's a backlash."

Those working to turn the state blue were thrilled to hear Mitt Romney call Arizona's stringent SB 1070 immigration measure "a model" for the nation's policies during a Feb. 22 debate in Mesa. They believe that kind of language -- underscored by Romney's endorsement on Sunday by Gov. Jan Brewer, who signed the bill into law -- could further mobilize Arizona voters looking for more moderate solutions to the immigration issue.

Harnessing that feeling on the ground will be the task of the campaign's substantial Arizona field operation.

The re-election campaign has three field offices already in Arizona -- in Phoenix, Tucson and Flagstaff -- and another set to open in heavily Hispanic Glendale in the coming weeks. The campaign says that staff and volunteers have held almost 500 voter registration sessions and more than 200 phone banks since the spring. Much of that effort is focused on the Hispanic community, with events held at Hispanic supermarkets and weekly Spanish- and English-language phone banks targeting Latinos. The campaign recently hired a Mexican-American regional field director.

While Team Obama hasn't yet invested in paid media there, the DNC has aired TV advertisements, including a six-day anti-Romney buy last year.

With the number of voting age Hispanic citizens growing by a whopping 85% last decade, per Census data, the benefits of such a focus are obvious. But the lift may still prove to be a heavy one.

The NBC/Marist Arizona survey this month also found that 51% of Hispanics approve of the president's performance, with 34% disapproving and 15% unsure.

Compare that to the 2008 numbers: Obama won 56% of the Latino vote in Arizona compared to McCain's 41%.

Luis Heredia, the executive director of the Arizona Democratic Party, estimates that Obama would have to boost that number to at least 65% in November to get over the finish line.

And Dill, who served as deputy state director for the Clinton/Gore win in 1996, puts that number even higher, at 68%.

He added that Democrats must be careful in 2012 to tailor their message to a diverse Hispanic community, saying that the party stumbled in past elections by treating the group as a single monolithic block.

"A big part of it had been our fault as campaign managers, as leaders," Dill said. "We had sort of homogenized the Hispanic community in Arizona into one group. And they're not, they're very diverse."

This year, Democrats say there's plenty of reasons to be optimistic.

Obama's team points to Democrats' double-digit mayoral victories in Tucson and Phoenix last year as well as the recall of Arizona State Senate president and author of SB 1070.

And Heredia adds that downballot races, like the one to replace retiring Rep. Gabby Giffords, will help build excitement for activists locally.

"I gain more and more confidence every day," he said.

Relishing a political victory, President Barack Obama said Tuesday that Congress "did the right thing" by extending payroll tax cuts for millions of Americans. He urged lawmakers to push forward on more measures, from assistance to struggling homeowners to increased taxes on the wealthy, saying the looming election was no excuse for inaction in Washington.

Larry Downing / Reuters

President Obama speaks about the importance of the passage by Congress of the extension of the payroll tax cut and unemployment insurance.

"Don't stop here. Keep going,'" Obama said during a White House event marking the passage of the tax cuts.

"Keep taking the action that people are calling for to keep this economy growing. This may be an election year, but the American people have no patience for gridlock," he said.

See related story: White House on defense over gas prices

Obama was celebrating a tax cut that is already in place, but due to expire at month's end. He said the extension of the tax cut for the rest of the year will have a spillover effect: More people will spend money and more businesses in turn will be prodded to hire workers, and so "the entire economy" gets a boost.

Congress overwhelmingly passed the $143 billion measure on Friday. The bill extends both a 2 percentage point reduction in the tax that funds Social Security and extends jobless benefits for the long-term unemployed. The measure also averts a big cut in the reimbursements doctors get for treating Medicare patients.

But Tuesday's event was not a bill-signing because the bill is not yet in Obama's hands. Not knowing when the legislation will come down from Capitol Hill, the White House decided to go ahead and hold its event now, while the victory is still fresh in people's minds. No major event is planned for the actual bill-signing.

The payroll tax cut was a centerpiece of the jobs plan Obama unveiled last year — and of a re-election strategy that seeks to cast his GOP foes as protectors of the rich out of touch with the worries of working families.

Obama never mentioned that a real driver of the deal Congress approved Friday was the political fallout on Republicans if they didn't give ground. Having endured a debacle in December, when they were seen as holding up the tax cut before caving, Republicans this time went along, and without demanding that the cost be paid for, either.

The White House said the average family would have lost $40 per paycheck had the tax cut not been extended. Throughout the payroll tax debate, the White House encouraged people to write in on social networking sites about how losing that money would affect their lives.

Several members of the public who submitted their thoughts were invited to join Obama at events promoting the tax cuts, including his remarks Tuesday.

"This got done because of you," Obama said. "Because you called, you emailed, you tweeted your representatives and you demanded action. You made it clear that you wanted to see some common sense in Washington."

White House officials have called the payroll tax cut the last "must-do" legislation Obama has to work with Congress on ahead of the November presidential election. Still, Obama made a push Tuesday for several other priorities outlined in his jobs bill and last month's State of the Union address, including legislation to assist small business owners and struggling homeowners.

Obama earlier this month proposed a vast expansion of government assistance to homeowners that would make lower lending rates a possibility for millions of borrowers who have not been able to get out from under burdensome mortgages. The proposal has special resonance in election battlegrounds such as Nevada and Florida that have faced record foreclosures.

Obama wants Congress to pass legislation that would make it easier for more borrowers to refinance their loans, creating a new program through the Federal Housing Administration that would have the government assume the risk for the new mortgages. The proposal faces a difficult path in Congress.

Obama also said he wants Congress to pass the so-called Buffett rule, which seeks to ensure that people making more than $1 million a year pay at least 30 percent of their incomes in taxes.

Mark Wilson / Getty Images

Health and Human Services Secretary Kathleen Sebelius defended the Obama administration's ruling that religious-affiliated institutions must include birth control as part of their health insurance plans.

Testifying before the Senate Finance Committee Wednesday, Health and Human Services Secretary Kathleen Sebelius defended the Obama administration’s ruling that religious-affiliated institutions must include birth control as part of their health insurance plans.

On Friday the administration announced a modification that allows religiously-affiliated employers to shift contraceptive costs to insurance companies. For some Democrats, such as Sen. Ben Nelson of Nebraska, President Obama still hasn’t settled the question of how to treat the employers who self-insure and do not contract with an insurance company to cover their employees.

But Obama seems to have quieted at least some dissident Democrats by issuing last week's adjustment. And that may be all he needs to do in order to defuse the political problem in his own party that the HHS contraceptive mandate created.

Related: Obama revamps contraceptive policy

With the election-year furor over contraceptives seemingly abating, Sebelius and Obama face a far larger imponderable: whether they will be able to implement the highly complex health care law -- even if it survives a Supreme Court decision on its constitutionality, which will come this June.

Three days of oral arguments before the high court begin March 26.

Meanwhile, Sebelius and her department are working with state governments to set up the new state-based insurance marketplaces, or “exchanges” in which uninsured American will be able to buy coverage, beginning in 2014.

According to the National Conference of State Legislatures, at least 22 states have legislation pending to establish a health insurance exchange. But some states are refusing to set them up, and others have joined the litigation to overturn the health care law.

“Right now I think it’s impossible to tell you exactly how many states will have a state-based exchange” Sebelius told Finance Committee Chairman Max Baucus, D- Mont., “What I am confident about,” she said, is the states will begin enrolling individuals in fall of 2013 so the exchanges can be operating by 2014.

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One Finance Committee Democrat, Sen. Jeff Bingaman of New Mexico, told Sebelius he was worried about states setting up information technology systems to run their exchanges that will be unable to communicate with each other and unable to provide data for the HHS. Bingaman said he was concerned about “everyone inventing the wheel in every state in the union.”

Sebelius replied, “Your concern is well-placed and well-founded” and described steps HHS is taking to ensure IT compatibility and more uniformity across state lines.

Another Democrat on the committee, Sen. Bob Menendez of New Jersey, illustrated the complexity of the 2010 law when he complained to Sebelius about three problems that he said HHS was slow in resolving: defining behavioral treatment to cover treatments for autism (New Jersey has the highest incidence of autism of any state), a program for treating post-partum depression for mothers, and a waiver for the state’s Medicaid program from certain federal regulations.

Menendez told Sebelius it was “frustrating” to be kept in the dark about the Medicaid waiver because the process “goes on behind closed doors without public notice and certainly without public input.”

After the hearing Menendez said of his three concerns: “I am waiting for them to act upon them and I am concerned in some ways about how they are acting upon them,” he said. Sebelius’s answers   “are not totally satisfactory.”

And not surprisingly, Republicans continued their strategy of predicting failure for Obama’s health care overhaul, which every Republican senator voted against in 2010.

Sen. John Cornyn, R- Texas, told Sebelius that “the administration has grossly underestimated the number of employers who will drop their employees from coverage” and “the costs will explode” for the health care exchanges. But Sebelius cited the insurance overhaul signed into law by former Massachusetts Gov. Mitt Romney as evidence that when insurance buying exchanges are set up, employers do not drop workers’ coverage.

Sen. Orrin Hatch, R-Utah, the ranking Republican on the Finance Committee, told reporters after the Sebelius hearing: “She’s pretty well admitted that they’re way behind on their regulations, they’re way behind on implementation, they’re way behind on exchanges.”

The most significant and intricate features of the law, such as the exchanges and the requirement for virtually all Americans to buy insurance, if they’re not already covered, will take effect in 2014.

“That bill is going to be almost impossible to implement and I think they are starting to realize that,” Hatch said.