Mitt Romney was desperate for a stronger performance in Florida's Republican debate on Monday to restore momentum to his campaign, and he delivered one with repeated sharp attacks on rising rival Newt Gingrich.
Often derided as a lukewarm debater, Romney lashed out at Gingrich for resigning as speaker of the U.S. House of Representatives under an ethical cloud and repeatedly labelled him an influence peddler.
The former Massachusetts governor needs a victory in Florida's primary on January 31, after he and two other rivals split the first three contests in the race for the nomination to oppose Democratic President Barack Obama in November's election.
New opinion polls show that Gingrich has jumped into the lead in Florida, after a convincing victory over Romney in South Carolina's primary on Saturday. The first few days of the Florida primary campaign have been a straight two-man race.
Romney kept on message on Monday by seeking repeatedly to tar Gingrich as a Washington insider who lobbied for clients including the troubled mortgage giant Freddie Mac.
In the 15 years after he left the speakership, the speaker has been working as an influence peddler in Washington, Romney said.
Romney took a much tougher tone than he did last week during a debate in South Carolina, when he stumbled in response to questions about his tax records and Gingrich.
I learned something from that last contest in South Carolina, and that was I had incoming from all directions, was overwhelmed with a lot of attacks. And I'm not going to sit back and get attacked day in and day out without returning fire, Romney said.
Gingrich shot back with a new attack on Romney's record, but he was mostly on the defensive, a departure from recent debates when he has dominated the stage.
In 2006 when you chaired the Governors Association, we lost governorships. And in the four years that you were governor, we lost seats in the Massachusetts legislature. So I think as a party builder, the 20 years I spent building the House Republican Party stands pretty good as an example of leadership, Gingrich said.
He staunchly denied he had ever worked as a lobbyist.
But despite the exchanges, the mood in the hall at South Florida University seemed almost subdued.
The crowd respected a request not to cheer during the discussion, and there were few red-meat lines like Gingrich's attacks on the media in South Carolina when he was asked about one of his divorces.
Romney's staff said that the more sterile debate format, without crowd reactions, benefited Romney.
One of the big dynamics is when there's not a big crowd that's hooting and hollering, it becomes a very different debate, Stuart Stevens, Romney's chief strategist, said. It becomes more of an examination of ideas and less sort of a game show environment and more of a serious debate.
But Romney did make what appeared to be a blunder when he suggested illegal immigrants should practice self-deportation instead of being rounded up and shipped home.
The answer is self-deportation, which is people decide they can do better by going home because they can't find work here because they don't have legal documentation to allow them to work here, and so we're not going to round people up, he said.
The other candidates, Texas Congressman Ron Paul and former U.S. Senator Rick Santorum of Pennsylvania sought to make a mark after finishing far behind in South Carolina, but neither had much of an impact as the frontrunners traded insults and barbs.
Santorum was declared winner of Iowa's January 3 caucuses last week after certified results reversed what had been called a narrow victory for Romney. Romney won the January 10 primary in New Hampshire, before Gingrich's big win in South Carolina.
In Florida, a Rasmussen Reports telephone survey of likely Republican voters put Gingrich on top of Romney by 9 percentage points and an Insider Advantage poll showed Gingrich ahead by 8 points
Romney used a question about his tax returns as an opportunity to outline his proposals to change the tax system. He joked that the country needed to get more people back to work so they could begin to pay taxes.
He promised to release his 2010 tax return and his estimated 2011 taxes on Tuesday, although he has been criticized for failing to release more years' returns.
You'll see my income, how much taxes I've paid, how much I've paid to charity. You'll see how complicated taxes can be. But I pay all the taxes that are legally required and not a dollar more. I don't think you want someone as the candidate for president who pays more taxes than he owes, Romney said.
The records, which were released after the debate, showed Romney will pay $6.2 million (3.9 million pounds) in taxes on a total of $42.5 million in income over the years 2010 and 2011. They indicated that he and his wife, Ann, paid an effective tax rate of 13.9 percent in 2010. They expect to pay a 15.4 percent rate when they file their returns for 2011.
To distract from his own financial questions, Romney called on Gingrich before the debate to disclose his contract for Freddie Mac, from which Gingrich made $1.6 million.
Gingrich's former consulting firm released a contract he signed with the company in 2006, but it shed little light on what Gingrich was hired to do. The document called for a $300,000 retainer and $25,000 in fees monthly for the year.
The debate, sponsored by NBC, National Journal and the Tampa Bay Times, was the 18th of the 2012 election cycle, and the first of two this week. A second is scheduled for Jacksonville on Thursday.
(Additional reporting by Steve Holland in Tampa and Kim Dixon and Lily Kuo in Washington; Editing by Peter Cooney and Paul Simao)