Mitt Romney painted rival Newt Gingrich as a Washington "influence peddler" who was unfit to lead the nation on Monday at the start of a bitter Republican presidential debate.
Romney, once considered the presumptive nominee, opened the debate in the Florida primary swinging at Gingrich's record, as he tried to regather a poll lead in the Sunshine State that had appeared unassailable just a week ago.
"I think this is going to come down to a question of leadership," said Romney, castigating Gingrich's stints in Washington as a lawmaker and as a lobbyist and throwing them up as evidence the former speaker of the House of Representatives is unfit to lead.
"In the 15 years after he left the speakership, the speaker has been working as an influence peddler in Washington."
Two new polls showed Gingrich overtaking the former Massachusetts governor in Florida, which votes next on January 31 and could either confirm Gingrich's surge or reinstate Romney as the frontrunner.
Gingrich tried to rise above the particularly personal attacks, claiming that Romney had said "at least four things that are false."
"I don't want to waste any time on it," he said, "It is the worst kind of trivial politics."
"Governor Romney can't tell the truth," he said, echoing criticism from Democrats about his opponent's consistency on key issues.
Romney, a multimillionaire businessman. has struggled to win over the Republicans conservative base who remain wary of his Mormon faith and his changing positions on key issues such as abortion and gay marriage.
For his part, Gingrich has tried to brush aside accusations of erratic, chaotic leadership in Congress when he was also hit by an ethics inquiry, as well as overcome questions over his marital infidelities.
Gingrich's resounding victory in South Carolina turned the race on its head, and his political resurrection ensures a dramatic battle to be the standard-bearer against Democratic President Barack Obama on November 6.
In the lead-up to the debate, Romney called on Gingrich to release his contract with mortgage giant Freddie Mac -- blamed for helping to cover up the depth of America's housing bubble which collapsed plunging the nation into recession, hitting Florida particularly hard.
"The speaker has been working over the last 15 years on K Street in Washington. It's a form of influence peddling or lobbying depending on whose definition you want to use, but basically he's connecting corporations with government," Romney told Fox News.
Gingrich, who was paid some $1.6 million in consulting fees for what he called his advice as a "historian" to the company, readily obliged, releasing his contract just hours before the debate.
It was immediately unclear if there was anything damaging in the release beyond his substantial financial ties to the mortgage firm.
Obama's reelection team also twisted the knife Monday, seeking to add to Romney's pain, in a clear sign that the president's brain trust would rather face Gingrich in November, believing he is easier to beat.
"This week Florida's voters will meet a candidate with no core values who believes he's entitled to play by a different set of rules," Obama campaign manager Jim Messina said in a memo.
A Rasmussen poll found Gingrich was now running at 41% in Florida, with his rival at 32%. Just last week, Romney had a 22-point lead in the Sunshine State.
A second poll by InsiderAdvantage/Majority Opinion Research had Gingrich leading by 34.4% to 25.6%.
Florida is a far larger and more diverse state than the others which have so far voted, where Romney will be hoping that his campaign war chest and well-oiled machine will give him the edge.
More than 220,000 voters have already cast early ballots, a state party official told AFP. And the Rasmussen poll found Romney was leading in those votes by about 11 %age points.
Former US senator Rick Santorum was running third in Florida at 11%, with libertarian congressman Ron Paul at 8%.
Gingrich was also boosted by news, reported by Politico, that key backer Sheldon Adelson, a billionaire American casino and hotel magnate, would inject another $5 million into his campaign support group.