Republicans have a race on their hands.

Just days after Mitt Romney seemed poised for a three-for-three streak in the opening presidential primaries, Newt Gingrich ensured the nomination fight will drag on after surging to a decisive victory in the South Carolina election Saturday night.

The candidates head next to Florida, which is now expected to be a grueling contest ahead of the Jan. 31 vote -- one which will test Gingrich's organizational strength as well as Romney's positions on issues like immigration.

Gingrich claimed Saturday that he's got "ideas" on his side, while Romney previewed a more aggressive strategy against Gingrich which will be more critical of his record in government.

"I don't shrink from competition," Romney said.

Gingrich, still looking to convey the image of a general election candidate, focused his victory speech almost entirely on President Obama Saturday, unloading some of his toughest criticism to date on the White House incumbent.

"He makes Jimmy Carter look strong," Gingrich quipped at the close of his speech.

Gingrich faces organizational challenges, but said he would rely on message to propel him forward. "We don't have the kind of money at least one of the candidates has, but we do have ideas and we do have people."

Gingrich locked up a decisive victory in the state. With 100 percent of precincts reporting, Gingrich pulled in 41 percent of the vote, to Romney's 27 percent. Rick Santorum finished in third with 17 percent, followed by Ron Paul with 13 percent. Herman Cain, who dropped out before the first contest, garnered 1 percent.

The leader board virtually ensures a drawn-out Republican race, a turnaround from just a week ago when Romney seemed poised to clinch the nomination in short order. While South Carolina has predicted the presidential candidate every year since 1980, the candidate in previous victories had won either Iowa or New Hampshire.

That was not the case now, as Santorum reflected.

"Three states, three winners. What a great country," Santorum said, referencing his first place showing in Iowa and Romney's victory in New Hampshire.

Romney, at his post-election rally in South Carolina, acknowledged that he sees a "long primary season" ahead and vowed to put up a stiff fight.

"I'll keep fighting for every single vote. I will compete in every single state," Romney said.

Gingrich surged to win South Carolina after what was arguably the most eventful week of the primary season, including. Rick Perry dropped out of the race Thursday, throwing his support behind Gingrich. The Iowa Republican Party dropped the surprise announcement that Santorum, and not Romney, had actually won the Iowa caucuses.

And Romney found himself repeatedly struggling to answer questions -- pushed by the Gingrich campaign and echoed in the media -- about his decision to not release his tax returns before April. Meanwhile, Gingrich was able to deflect questions about allegations from his second wife that he once sought an "open marriage."

His scorching answer at Thursday's debate to a question on the subject, which earned him a second standing ovation in one week, may even have helped improve his standing ahead of the South Carolina vote, as exit polling showed a plurality of women voters supported him over his rivals.

In the delegate battle, Fox News projected Gingrich will win at least 19 of South Carolina's 25 delegates. That puts him in second place behind Romney in the overall race for the nearly 1,144 delegates needed to clinch the nomination.

With a victory under his belt, Gingrich held back Saturday night on criticism of his opponents, instead commending them for their contributions to the debate. Rather, he unleashed a tirade of criticism on Obama, describing him again as the "most effective food-stamp president in American history" and excoriating him for his recent decision to deny a permit for the Canada-to-Texas Keystone pipeline.

Warning that the decision would drive the Canadians to strike an oil deal with China, he said: "An American president who can create a Chinese-Canadian partnership is truly a danger to this country."

Romney, who for much of the race tried to focus his criticism on Obama, signaled Saturday he will step up his attacks against Gingrich in the upcoming contests.

The former Massachusetts governor, without calling out Gingrich by name, blasted him over his government-heavy resume and his past attacks on Romney's tenure at Bain Capital.

"Those who pick up the weapons of the left today will find them turned against us tomorrow," Romney warned.

Likewise, Romney said the GOP can't defeat Obama with a candidate who joined in on the "assault on free enterprise."

"They're attacking every person who dreams of a better future. He's attacking you. I will support you," Romney said, adding that anyone who demonizes success is not "fit" to be nominee.

Fending off calls for Romney's tax returns, Romney aides told Fox News there is no plan "at this time" to accelerate the release, but there is clearly a debate over the topic within the campaign.

One Romney adviser told Fox News that the campaign is "happy" with the state of the race.

"You never get to the end zone without being tired and taking hits," said adviser Stuart Stevens.

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The other two candidates said they're staying in the race.

Santorum, speaking Saturday night in Charleston, described the contest as "wide open" and said he's charging into Florida next.

He continued to make a working-class appeal to voters, saying he's going to bring a "little different message" than the other candidates.

"I plan to be a little different," Santorum said. "I'm going to go out and talk about how we're going to have a Republican Party, a conservative movement that makes sure that everyone in America has the opportunity to rise."

Paul, despite placing fourth, vowed to press on Saturday night. He noted that the returns suggest his campaign will have attracted four or five times more votes than it did in the 2008 race. He added that being in the race had propelled forward the issues he's been pushing for decades.

"I have been in this business of promoting this cause in the electoral process for a long time. At the beginning, I thought it was just going to be promotion of a cause. Then it dawned on me, if you win elections and win delegates, that's the way you promote a cause," Paul told an enthusiastic crowd. "This campaign has a long way to go."

Exit polling confirmed Gingrich's growing advantage in the race ahead of Saturday's results. Those who made up their minds late broke for Gingrich, while those who had decided early mostly backed Romney. Late deciders outnumbered early deciders 53-46 percent. Gingrich also had the advantage among voters who viewed the debates as important. And Gingrich led among those who say it's important that a candidate shares their religious beliefs.

The race heads next to Florida. There, Romney is planning to aggressively go after Gingrich's ethics record in the House during his days as speaker and the consulting work his firm did for Freddie Mac.

In a fresh fundraising pitch, Gingrich continued to press the case that he is the "Reagan conservative" the party needs to go up against Obama.