Former speaker of the House Newt Gingrich has won the S.C. first-in-the-South primary.
With 99 percent of the precincts reporting, Gingrich led former Massachusetts Gov. Mitt Romney by 41 percent to 28 percent.
Gingrich won 29 of the first 30 counties with full tallies. Romney won in Charleston County and was leading in Richland County.
Republican voters, angry at the sluggish economy and a nearly double-digit unemployment rate, brushed aside concerns about Gingrich's past personal life woes, and chose him as the one best prepared take the fight to President Barack Obama in November.
"Thank you South Carolina!," Gingrich tweeted. "Help me deliver the knockout punch in Florida," which holds the next primary on Jan. 31.
Obama is "the most effective food stamp president in history," he said during his victory speech at the Hilton Columbia. "I would like to be the best paycheck president in American history."
South Carolina has elected the candidate who eventually won the GOP presidential nomination in every cycle since Ronald Reagan in 1980. A New York Times analysis said Gingrich had a chance to sweep all 25 S.C. delegates to the GOP convention -- the 11 given to the winner and two each awarded for winning in each of the state's seven Congressional districts.
At the beginning of the week, Romney seemed headed to win his third primary win in a row. He was polling well ahead of Gingrich, up 19 points in a CNN poll two weeks ago and up 10 points early this week.
But two well-watched debates in the crucial days leading up to the primary -- when many S.C. voters were just tuning in -- proved a game changer for Gingrich whose fiery debate style galvanized voters and gave credence to their anger at Washington.
In contrast, Romney stumbled over questions about releasing his federal tax records.
Gingrich then received support from former vice presidential candidate Sarah Palin, who said this week that she would vote for his if she could vote in the South Carolina primary. Her husband, Todd, had endorsed Gingrich. He also received the endorsement of Texas Gov. Rick Perry when he dropped out of the race on Thursday.
Soon after, Iowa officials declared former U.S. Sen. Rick Santorum the winner of its caucus after a recount, leaving Romney with just a victory in New Hampshire, a state that borders Massachusetts.
"I took Iowa and Newt took South Carolina, and it's game on again," Santorum told CNN.
Based on exit polling, Fox, ABC, NBC, CBS, CNN and The Associated Press called the race soon after voting booths closed at 7 p.m.
Gingrich was favored heavily in polls by voters who identified themselves as evangelical, Tea Party or very conservative -- despite a national TV interview with his second wife where she said he wanted an open marriage in order to continue his affair with a woman who became his third wife.
Romney, who had the endorsement of S.C. Gov. Nikki Haley, worked to convince voters in a state with one of the nation's highest unemployment rates that his business experience made him best suited to fix the economy.
"You should hear them when we win," Romney said after his supporters cheered him at the S.C. State Fairgrounds.
He took aim at Gingrich: " "Our party can't be led to victory by someone who has never run a business and never run a state."
Santorum, who received the endorsement from a group of national religious leaders last week, was leading Texas Congressman Ron Paul for third place in South Carolina in early results. Paul has not finished worse than third in the first two primaries.
With 99 percent of the S.C. precincts reporting, Santorum had 17 percent of the vote compared to Paul's 13 percent.
Two candidates, Perry and former Utah Gov. Jon Huntsman, dropped out of the race this week. Both were polling in single digits in South Carolina after failing to nab a top-two finish in Iowa or New Hampshire.
Herman Cain, who dropped out of the race in December, received the fifth-biggest total of the night at 1 percent. Comedian Stephen Colbert, who missed the deadline to get on the ballot in his home state, asked South Carolinians to cast vote for Cain as a show of support for him. Cain received little more than 6,300 votes.
A rainy Saturday appears to have curbed turnout in some areas but that did not halt a bit of primary-day political theater over dueling appearances at a Greenville restaurant among the race's front-runners.
Turnout was heavier than normal in some portions of Charleston, Calhoun, Georgetown, Greenville, Kershaw, Pickens, Richland, Saluda and York counties, the state election commission reported based on anecdotal responses from county elections offices.
Turnout was light in Allendale, Bamberg, Dillon, Hampton, Jasper, Newberry, Orangeburg, Union and Williamsburg counties, most of which lean Democratic.
Gingrich and Romney nearly met at Tommy’s Country Ham House in Greenville when they both scheduled appearances at 10:45 a.m.
Romney showed up nearly an hour early. He sounded like he expected to lose.
"We'd like to win here, of course, but we have a long way to go," he told the crowd. "So come join us in Florida, then in Nevada, Michigan, Colorado." Nevada holds caucuses Feb. 4, while Michigan and Colorado have primaries Feb. 7.
Romney stressed his business experience and criticized Obama. "If we think we need a Washington insider to run Washington there are a lot of people to choose from, but I’m the only guy whose spent his life in the real world — I’m going to fight to put America back to work,” he said.
Romney spent about 15 minutes at the ham house. He left before Gingich showed up.
When Gingrich appeared about a half hour after Romney left, he said, "I was hoping for a debate. Where's Mitt?"
He urged the crowd to reject "the arrogance and dishonesty of the Romney campaign," and stayed about 45 minutes.
Joey Holleman, The Associated Press and The McClatchy Washington bureau contributed