In the most extraordinary day of the Republican presidential race, a series of fast-paced and unexpected events shook the candidates and their campaigns Thursday, significantly changing the dynamic of the contest just two days before a crucial primary that many thought might settle the nomination.

It was a day of split-screen viewing and almost hourly recalibration. Iowa Republicans declared former senator Rick Santorum (Pa.) the new winner of their Jan. 3 caucuses, erasing Mitt Romney’s eight-vote victory. Texas Gov. Rick Perry, who had one of the largest donor networks of any candidate, quit the race and endorsed former House speaker Newt Gingrich, who was gaining momentum but faced new challenges as an ex-wife accused him in two interviews of asking for an “open marriage.”

And that was all before mid-afternoon. Thursday was capped by the second candidate debate in four days, this time with just four contenders — Romney, Gingrich, Santorum and Rep. Ron Paul (Tex.) — onstage and with more at stake than in any of the previous forums.

The debate was more evenly balanced between the two front-runners than a forum earlier in which Gingrich gained the upper hand. Santorum was especially aggressive in challenging his rivals, but saved his most pointed criticism for Gingrich, saying his temperament and style would make him a risk to lead the party against President Obama in November.

The most electric moment came at the start, when Gingrich, to enthusiastic applause, rebuked moderator John King of CNN for raising the issue of his ex-wife’s interview. Calling it “trash” and “as close to despicable as anything I can imagine” to open the debate on that topic, he said he was “appalled” by the question.

But the fireworks began long before the cameras started rolling. For the first time on Thursday, a race that only a few days earlier appeared to be almost on autopilot — with Romney in control and looking to wrap up the nomination quickly — was suddenly careering toward Saturday’s primary with Romney, a former Massachusetts governor, fighting to avoid a potentially costly defeat by Gingrich that would send the race on to Florida for a Jan. 31 primary.

The news represented potential problems for Romney, whose missteps earlier in the week helped breathe life into the contest. Whether he was in genuine trouble was not clear, but by Thursday afternoon there was at least a sense that the contest was again in flux.

The candidates appeared at multiple events on Thursday and the airwaves were packed with vivid advertisements that competed with the stream of breaking political news. Adding to the carnival atmosphere was a planned appearance by comedian Stephen Colbert and a speech by Herman Cain, the former pizza company executive who dropped out of the race weeks ago, at the Southern Republican Leadership Conference in Charleston.

The swift developments of the adrenaline-fueled day were another example of how the Republican contest has defied easy characterization from the start. And they helped South Carolina begin to live up to a reputation of delivering memorable and hotly contested primaries.

Romney fought back against suggestions that he is slipping, targeting Gingrich and calling on surrogates to reprise a charge — that the former speaker is an “unreliable leader” — they used when Gingrich first emerged as a threat late last year.

As Obama prepared to deliver a speech at Walt Disney World in Florida, Romney said: “He may bump into Speaker Gingrich down there, in Fantasyland. I only say that because the speaker was talking about all the jobs that he helped create in the Reagan years. He’d been in Congress two years when Reagan came to office. The idea that he was the author of Reaganomics — not real likely.”

Romney advisers, having survived ups and downs over the past year, sought to portray the events as minor bumps, issuing a statement calling the Iowa results a “virtual tie” and playing down Perry’s endorsement of Gingrich.

“We won’t do anything differently today than we did yesterday,” said Stuart Stevens, Romney’s chief strategist. “I think we would get Perry voters. This thing’s never monolithic. Mitt Romney has the highest favorables of any candidate, a strong message, and most people want to beat Barack Obama, and Mitt Romney overwhelmingly is the best candidate to do that.”

Gingrich seemed to be enjoying a sudden burst of momentum — drawing enthusiastic crowds, picking up new endorsements and ticking upward in multiple polls. But he faced his own possible setback after the second of his three wives gave interviews to The Washington Post and ABC News describing her husband’s infidelity.

Campaigning in Beaufort, Gingrich called Marianne Gingrich’s interview “tawdry” and tried to focus attention on happier news. In addition to Perry’s support, he noted that former Alaska governor Sarah Palin had recently said he would be her choice.

“There are a lot of different things coming together across the whole state,” he said.

The first news on Thursday about the contest broke before dawn, with a report in the Des Moines Register that a new vote count in Iowa showed Santorum 34 votes ahead of Romney, but with results in eight precincts still missing. Later in the day, the Iowa Republican Party declared Santorum the winner, denying Romney the claim that he had made history as the first non-
incumbent Republican to win both Iowa and New Hampshire.

Hours later, Perry declared: “I have come to the conclusion that there is no viable path to victory for my candidacy in 2012.”

The Texas governor, who entered the race to great fanfare in August but quickly sank under the weight of his poor debate performances, was never expected to play a major role in South Carolina. In his endorsement, Perry acknowledged Gingrich’s flaws, describing him as “not perfect,” before adding: “But who among us is? There is a forgiveness for those who seek God.”

Gingrich advisers said they see a series of potential benefits. One insider, who spoke on the condition of anonymity in order to share the information, said the decision will help to clarify the nomination battle along a conservative-liberal axis. Gingrich’s team believes Romney cannot win that fight.

Gingrich’s campaign also considers Perry someone who can open doors to donors. And the governor could swing support to Gingrich in Texas, with enough of a dividend in delegates to make up for his absence from the ballot in Virginia.

But Romney saw a benefit to Perry’s departure, too, as Dirk Van Dongen, a prominent lobbyist who had backed Perry, quickly changed his loyalty to Romney.

“He’s going to be the nominee in my judgment, and it’s time for us to come together,” said Van Dongen, head of the National Association of Wholesaler-Distributors.

Santorum, meanwhile, embraced the news from Iowa.

“We feel very very good about what this win will mean,” he said. “It says that we can win elections. We can organize. We can put together an effort to pull the resources together to be able to be successful and be the person who can defeat Mitt Romney. Because guess what: We defeated Mitt Romney in Iowa.”

A longtime Santorum supporter put it more bluntly.

“Romney has now won one state — that he practically lives in — and Santorum has won one state,” said Stuart Roy, an adviser to the pro-Santorum Red, White and Blue PAC. Santorum also received the endorsement of social conservative leader James Dobson, who was part of the group that met last weekend in Texas to try to consolidate support among conservatives. But the latest polls show Gingrich gaining, not the former senator.

Cillizza reported from Washington. Staff writers Dan Eggen in Washington and Rosalind Helderman, Nia-Malika Henderson, Philip Rucker and Karen Tumulty in South Carolina contributed to this report.


Gloves come off in final South Carolina debate

The Fix: S.C. Debate’s winners and losers

Fact Checker: 15 dubious debate statements

Senate delays vote on anti-piracy bill PIPA

Marianne Gingrich, Newt’s ex-wife, says he wanted an ‘open marriage’