COLUMBIA, S.C. - (2nd UPDATE) Republican presidential candidate Newt Gingrich trounced frontrunner Mitt Romney in South Carolina on Saturday in a jarring victory that indicates the party's battle to pick a challenger to President Barack Obama may last months, not weeks.
Gingrich's come-from-behind triumph in the primary in the conservative southern state injects unexpected volatility into a Republican nominating race that until this week appeared to be a coronation for Romney, the former Massachusetts governor and private-equity chief.
Instead, voters in South Carolina rejected Romney's pitch that he is the best bet to fix a broken U.S. economy and defeat Obama, a Democrat, in the Nov. 6 election.
Three different candidates - Gingrich, Romney and former U.S. senator Rick Santorum - now have won the first three contests in the state-by-state battle for the Republican presidential nomination to face Obama.
Gingrich's triumph may lead to a protracted battle of attrition as Republican candidates spend millions of dollars to tear each other down rather than uniting behind a standardbearer to take back the White House.
With nearly all the votes counted, Gingrich had pulled in 40 percent of the vote, followed by Romney with 28 percent, networks reported. Santorum was in third with 17 percent and U.S. congressman Ron Paul in fourth with 13 percent.
The next contest is the Florida primary on Jan. 31.
Riding a series of feisty debate performances, the former speaker of the House of Representatives captured the lingering unease of conservative voters in South Carolina who view Romney's moderate past and shifting policy stances with suspicion. Gingrich argued that he would be able to better articulate the party's conservative ideals.
South Carolina was a stunning turnaround for Gingrich, whose campaign barely survived after top staff quit last June and stumbled to a disappointing finish just three weeks ago in Iowa, the first Republican nominating contest. He finished fourth in both Iowa and New Hampshire a week later as conservatives split their votes among several candidates.
Gingrich contrasted his sometimes-chaotic management style with Romney's buttoned-down approach, arguing that his campaign was powered by ideas rather than logistics. Romney is one of the wealthiest candidates ever to run for president and his campaign is well financed.
"We don't have the kind of money that at least one of the candidates have. But we do have ideas and we do have people," Gingrich told supporters in a 22-minute tirade against Obama, the news media, judges and other "elites."
Romney acknowledged that there will be a long primary season. He said he would continue to run on his business record and paint Gingrich as a creature of Washington in the weeks ahead.
"I don't shrink from competition, I embrace it," Romney told supporters. "I believe competition makes us all better. I know it's making our campaign stronger."
Obama, who does not face a primary challenger, will have his turn in the spotlight on Tuesday with his State of the Union address. In a message to supporters on Saturday, he said the speech would focus on "building an economy that works for everybody, not just a wealthy few."
On to Florida
Heading into Florida, Romney starts off with a wide lead in the polls and a distinct edge in logistics and fund-raising, which will be crucial in a state with 10 separate media markets.
Campaigns must spend at least $1 million each week to reach voters in the sprawling southern state, according to local political officials. Romney's allies have already spent $5 million, mostly on ads attacking Gingrich. No other candidate has a significant presence in the state.
Animosity between Gingrich and Romney has been festering since December, when a group supporting Romney launched a blitz of negative TV ads in Iowa that ruined Gingrich's campaign there. In South Carolina, a state with a reputation for rough and tumble politics, the gloves came off.
Gingrich attacked Romney's business record at private equity firm Bain Capital and his reluctance to release personal tax information, while Romney pointed to Gingrich's past ethics lapses and alluded to his messy personal life.
South Carolina Republican voters said they were focused on fixing the sluggish economy and finding the strongest candidate to defeat Obama. Some 78 percent said they were "very worried" about the economy and 45 percent said that the most important trait in a candidate was the ability to beat Obama, according to exit polls released by CNN.
Those issues are the twin pillars of Romney's candidacy.
But Gingrich's wide-ranging stump speeches and red-meat attacks against Obama convinced many voters that he had the fire in the belly to take on the incumbent.
"A vote for Newt was a vote against Obama," said Charleston photographer Kim Woods, who voted for Gingrich.
Romney saw his aura of inevitability erode in South Carolina after leading opinion polls by 10 percentage points a week ago. He suffered a setback on Thursday when Iowa officials declared in a recount that he had actually come in second place in that state, instead of winning narrowly as initially announced.
Romney took a swipe at Gingrich for criticizing his conduct at Bain Capital, calling it an "assault on free enterprise."
"Those who pick up the weapons of the left today will find them turned against us tomorrow," Romney told supporters.
Voters said they viewed Romney's business background as an asset. But he waffled this week when asked whether he would release his tax records, and acknowledged that he pays a much lower tax rate than many Americans, around 15 percent.
In his speech, Gingrich took aim at Obama, painting him as a weak president, "truly a danger to the country" with his energy policies and "out of touch with reality." He also lashed the news media and condemned what he called "the growing anti-religious bigotry of the elites" in America.
'Punch in the mouth'
"This is the punch in the mouth/wake up call Romney needed if he wanted to be a strong general election candidate," Republican strategist Ford O'Connell said in a Twitter message, referring to the South Carolina results.
Romney has attacked Gingrich's ties to mortgage giant Freddie Mac and criticized his time in the nation's capital. His campaign also highlighted Gingrich's $300,000 fine due to ethics lapses while serving as House speaker 15 years ago.
The thrice-married Gingrich has fended off publicity about his turbulent marital history. On Thursday, he rejected his second wife's accusation that he had asked her for an "open marriage" while he was having an affair with another woman in the 1990s.
South Carolina has been a tough state for Romney's presidential ambitions. In his previous run for the White House in 2008, Romney finished a poor fourth, with just 15 percent of the vote, behind winner and eventual Republican nominee John McCain. McCain endorsed Romney in the current campaign.
The winner of South Carolina's Republican presidential primary has gone on to win the party's nomination in every presidential election since 1980.
(Additional reporting by Colleen Jenkins, Deborah Charles, Alina Selyukh and Lily Kuo; Writing by Andy Sullivan; Editing by Will Dunham)