WASHINGTON (Reuters) - Republican U.S. presidential contender Mitt Romney, once the leader and presumed nominee, is back in front-runner mode.
Less than three weeks before Iowa kicks off the state-by-state Republican battle to find a challenger to President Barack Obama, polls show support for main rival Newt Gingrich may already be softening.
Romney also won an important endorsement on Friday from South Carolina Governor Nikki Haley.
With other contenders scrambling to slice up Gingrich, Romney was a model of decorum at the final Republican debate on Thursday before Iowa kicks off the nominating race on January 3.
Romney let rivals Ron Paul and Michele Bachmann lead the way in attacking Gingrich and stayed well above the fray. He even exchanged compliments at times with Gingrich, the former House of Representatives speaker who has rolled past him in polls in the last month.
"His whole goal now is to get back to being the 'safe and steady' candidate. He can let his surrogates do the work for him," Republican strategist Ford O'Connell said.
"He doesn't even need to win Iowa, he just needs to make sure that Gingrich doesn't - and Ron Paul and Michele Bachmann can help him with that."
After a week of intensifying criticism of Gingrich's temperament and judgment, climaxed when Romney called him "zany," his attack machine went dark when the debate lights went on.
A Rasmussen poll showed Romney, the former governor of Massachusetts, has a slight lead over Gingrich in Iowa, a state Romney has largely bypassed this year after spending millions there in 2008 only to lose.
Two other polls show Paul, a libertarian Republican congressman, moving into second place behind Gingrich in Iowa and gunning for an upset that would almost certainly help Romney by stopping Gingrich's rise.
Polls show Romney also still has a commanding lead in New Hampshire, the state where he has focused his efforts, putting him in prime position to put a stranglehold on the race with strong performances in the first two contests.
'WILL GO ON FOR A WHILE'
The next contest is in conservative South Carolina, followed by the big battleground state of Florida, an expensive state for advertising where the more moderate Romney has worked hard at organizing.
"Everybody wants to win Iowa and we all hope to do that, but this process is going to go on a while," Romney told Fox News after the debate.
Romney got a boost on Friday with a much-sought endorsement from Haley, a favorite of Tea Party conservatives who had been heavily courted by Romney's rivals.
South Carolina holds the third nominating contest after Iowa on January 3 and New Hampshire on January 10.
"The election next November will have ramifications for generations," Haley said in a statement released by the Romney campaign. "Neither South Carolina nor the nation can afford four more years of President (Barack) Obama, and Mitt Romney is the right person to take him on and get America back on track."
A fade by Gingrich would be fitting in a race that has seen multiple contenders - first Bachmann, then Texas Governor Rick Perry and then businessman Herman Cain - rise to the top only to fall back to the pack.
Romney, with a decided financial edge over Gingrich, will have a clear advantage the longer the race goes on. He launched a heavy wave of advertising attacks on Gingrich's temperament and electability this week.
He capped those attacks by calling Gingrich's ideas "zany" during a New York Times interview.
Gingrich obviously was paying attention.
"I'm very concerned about not appearing to be zany," he joked at one point during the debate.
In the debate, Romney sat back and let Bachmann and Paul batter Gingrich over his work for mortgage giant Freddie Mac, while former U.S. Senator Rick Santorum reminded voters Gingrich was not well liked as House speaker.
"Romney was back in front-runner mode tonight emotionally, if not statistically," Republican Dan Schnur, a former aide to John McCain's 2000 presidential bid, said of Romney's passive debate performance.
"This was the safe and careful Romney we've seen for most of the year," he said. "Maybe their internal polling is showing their attack ads on Gingrich are doing the job, so they didn't need to do it to his face."
(Editing by Alistair Bell)