Updated 10:25 p.m. Eastern Time
Newt Gingrich has soundly defeated Mitt Romney in the South Carolina Republican primary, a comeback victory that puts to rest Romney's hopes of effectively wrapping up the GOP presidential nomination by the end of the month.
Rick Santorum is finishing a disappointing third place in the deeply conservative Palmetto State, and Ron Paul finished in fourth.
"Thank you to everybody in South Carolina who decided to be with us in changing Washington," Gingrich, who hails from nearby Georgia, told cheering supporters in South Carolina Saturday after his double-digit victory.
The former House speaker attributed his victory to the notion that "the American people feel that they have elites who have been trying for a half century to quit being American and become some other system." Gingrich, a longtime Washington power broker, repeatedly criticized "the elites in New York and Washington" in his remarks.
Gingrich largely spoke positively of his rivals but harshly criticized President Obama, who he suggested was moving America toward a "secular, European-style bureaucratic socialist system." (Watch a clip at left.)
With nearly all precincts reporting, Gingrich had 40 percent of the vote, followed by Romney with 28 percent, Santorum with 17 percent and Paul with 13 percent.
Gingrich's victory brings fresh energy into his campaign -- which has twice been left for dead -- ahead of the Florida primary on January 31. For Romney, meanwhile, an opportunity to win the nomination and pivot to a focus on the general election before the spring was gone. South Carolina has voted for the candidate who went on to with the GOP nomination in every primary since 1980.
"We're now three contests into a long primary season," Romney told supporters Thursday night after learning he was projected to come in second place. "This is a hard fight because there's so much worth fighting for. We've still got a long way to go and a lot of work to do." (Watch a clip of his remarks at left.)
Romney spent most of the rest of his speech attacking President Obama, though he also criticized his GOP rivals for what he cast as their attacks on "free enterprise," a reference to attacks on his tenure running Bain Capital, a venture-capital firm that sometimes laid off employees at the companies it took over.
"The Republican Party doesn't demonize prosperity, we celebrate success in our party," he said, adding that Republicans who join Democrats in such criticisms "are not going to be fit to be our nominee." Gingrich has been an outspoken critic of Romney's tenure at Bain.
Gingrich's win was due in large part to his strong performance in two debates in the state this week. Nearly two in three GOP primary voters said the debates played an important role in their decision, and more than half (55 percent) made up their minds in the last few days, according to exit poll data.
Among these late-deciders, Gingrich was the clear favorite: 44 percent backed him, compared to 24 percent for Romney and 22 percent for Rick Santorum. And among the 65 percent who said the debates were an important factor, 50 percent backed Gingrich, while just 22 percent backed Romney.
In his remarks Saturday, Gingrich told supporters, "It's not that I am a good debater, it's that I articulate the deepest felt values of the American people."
The exit poll data show Gingrich winning among white evangelicals, who made up 64 percent of the electorate. Gingrich also held a strong lead over Romney among men (42 percent to 26 percent), conservatives (44 percent to 24 percent) and Tea Party supporters (45 percent to 25 percent).
Nearly half said the most important quality in a candidate is that he can beat President Obama in November; among this group, 51 percent supported Gingrich and 37 percent supported Romney. The notion that he is the most electable candidate has been a central argument from the former Massachusetts governor and if those numbers spread to other states, Romney could face serious trouble.
Gingrich's win recasts a race Romney seemed to be dominating just one week ago, when he had been declared the winner of the first two contests and was leading the polls in South Carolina. The past week has been one of the worst of Romney's campaign: He stumbled in the debates, at one point receiving a smattering of boos for equivocating over how many years of his tax returns he would release, and was stripped of his Iowa win after a recount. Romney, whose net worth is estimated at up to a quarter of a billion dollars, also acknowledged that his effective federal income tax rate is roughly 15 percent, lower than the rate paid by most Americans.
Gingrich, meanwhile, offered up two strong debate performances, including one on Thursday in which he earned a standing ovation for the way he swatted away a question about allegations from his ex-wife. The charges from Marianne Gingrich, who said Gingrich asked her for an open marriage involving the woman who would later become Gingrich's third wife, do not seem to have had a significant negative impact in South Carolina.
For Santorum, a third place finish in South Carolina is a blow. Santorum rose from relatively obscurity to do well in Iowa and eventually be declared the winner there, but he has lost the battle to become the consensus conservative alternative to Romney in South Carolina. The former Pennsylvania senator may struggle going forward for the donations he needs to compete in Florida, a large state with expensive rates for television ads. (Gingrich, by contrast, should see a fundraising boost that will boost his chances in the Sunshine State -- though Romney will have an organizational advantage, and likely maintain his financial advantage as well.)
Santorum vowed Saturday night that he would not leave the race, and his campaign pointedly sent reporters a Florida campaign schedule after the projection of Gingrich's victory. "It's a wide open race," he told cheering supporters. (Watch a clip at left.)
"Three days ago there was an inevitability in this race," Santorum told CNN in an interview as the results came down, noting that Romney was seen as the winner of Iowa and New Hampshire and was expected to with South Carolina. "I took Iowa, Newt took South Carolina, and it's game on again."
Santorum, who said Gingrich "kicked butt" in South Carolina, said a drawn-out nomination process is good for the eventual nominee -- and predicted of the GOP primary battle, "We're going to have it go on for a long time."
Paul did not put much focus on South Carolina. The Texas lawmaker, whose Libertarian views have attracted a fervent (if limited) following, is focused on building up his delegate count in all 50 states, and he is expected to have the resources to potentially remain in the race up until the nominating convention.
Paul told supporters the "cause of Liberty" is gaining ground in his remarks Thursday night, telling his backers that winning elections and building up delegates is "the way you promote a cause."
South Carolina exit poll
GOP delegate scorecard
Complete primary and caucus results