Miami (CNN) -- Mitt Romney and Newt Gingrich and their surrogates exchanged harsh attacks Wednesday as a new poll showed them in a statistical dead heat in Florida six days before the Sunshine State's primary in the Republican presidential race.
The CNN-Time-ORC International poll indicated that Gingrich surged after his 12-point victory in Saturday's South Carolina primary, but his momentum appeared to be slowing.
According to the poll, 36% of people likely to vote in Tuesday's Florida primary back Romney, while 34% are for Gingrich. Romney's margin is well within the survey's sampling error.
The poll shows former Pennsylvania Sen. Rick Santorum at 11% and Texas Rep. Ron Paul at 9%, with 7% undecided.
With the final debate in Florida to be broadcast Thursday night on CNN, the campaign intensified Wednesday with the two leaders, their surrogates and super PACs supporting them ratcheting up criticism of the other.
Gingrich, a former House speaker, disparaged Romney's personal wealth when asked about the former Massachusetts governor's call for illegal immigrants to deport themselves.
"I think you have to live in a world of Swiss bank accounts and Cayman Island accounts and automatic, you know, $20 million a year income with no work to have some fantasy this far from reality," Gingrich said at a "Meet the Candidates" forum in Miami, later adding: "For Romney to believe that somebody's grandmother is going to be so cut off that she is going to self-deport, I mean this verges -- this is an Obama-level fantasy."
Earlier, the Gingrich campaign acknowledged it had stopped running a Spanish-language ad that referred to Romney as "the most anti-immigrant candidate." The ad had drawn censure from Florida Sen. Marco Rubio.
Romney, asked later about the ad and Gingrich's criticism, said in the candidate forum, hosted by the Spanish-language network Univision, that such attacks were "unbecoming" for a presidential hopeful. Under the forum format, the candidates were interviewed separately.
"It's very sad for a candidate to resort to that kind of epithet," Romney said of the pulled ad. "There are differences between the candidates on these issues but we don't attack each other with those kind of terrible terms."
Romney also noted that Gingrich had previously supported the idea of self-deportation.
"I recognize that it's very tempting to come out to an audience like this and pander to the audience and say what you hope the audience will want to hear but, frankly, I think that's unbecoming of a presidential candidate," Romney said. "And I think that was a mistake on his part."
Meanwhile, veteran Sen. John McCain, who is backing Romney, accused Gingrich of encouraging an explosion of earmarks when he was speaker of the House that ultimately led to corruption in Congress.
"I saw these earmarks explode. I saw the corruption that resulted from it," the 2008 Republican presidential nominee said on a conference call with reporters organized by Romney's campaign.
Earmarks "dramatically expanded on Newt Gingrich's watch," McCain said, citing a memo he said Gingrich wrote in 1996 directing lawmakers in charge of spending decisions to "consider elections" when doling out earmarks.
McCain has long been a critic of earmarks -- money lawmakers direct to their home districts and states -- and he previously attacked Santorum on the same issue.
Gingrich's campaign pointed to an independent analysis showing that during at least one of the four years he was speaker, the number of earmarks dropped.
McCain also questioned whether Gingrich's leadership style was suitable for someone seeking the presidency, noting Gingrich lacked support to continue as House speaker in 1999.
"He could not have been re-elected as speaker of the House, and his leadership style was a major factor in giving him lack of support for re-election as speaker," McCain said.
Romney's campaign received a boost Wednesday by receiving the endorsement of the Orlando Sentinel, which backed McCain in 2008.
The paper, which circulates in the demographically diverse central area of the state, called Romney a "steady and competent leader for these divisive and turbulent times."
In appearances Wednesday across Florida, the candidates criticized President Barack Obama's State of the Union speech Tuesday night.
Obama's speech revealed him to be "extraordinarily detached from reality," Romney said in Orlando, highlighting what he said was the president's failure to mention the country's huge deficit.
"What he didn't say last night is that we are spending too much and borrowing too much and that America is on a collision course with debt and that if we don't get off this course, we could sink the American economy and go into calamity," Romney said.
Gingrich said at an event in Miami that Obama's proposal to ensure that millionaires pay at least 30% in capital gains tax "would be a disaster of the first order" if it meant doubling the 15% capital gains tax.
Such a move "would lead to a dramatic decline in the stock market, which would affect every pension fund in the United States," Gingrich said, adding it would also drive investment overseas and "would be the most anti-jobs single step he could take."
Asked Wednesday for details of the 30% tax plan, White House press secretary Jay Carney told reporters: "I'm not going to give you a schedule of how a broad individual tax reform would break down and what impact it would have on capital gains or dividends."
Santorum, who has argued he has the best chance of appealing to blue-collar, moderate voters in key swing states, responded to Obama's speech by saying the president had made his case for him.
"Barack Obama knows the key to this election are the swing states, in particular in the industrial heartland of our country," Santorum said. "Those are the folks who are being disaffected by policies that are crushing the manufacturing and processing sector of the economy."
Paul has decided not to spend money in Florida because of his poor prospects in its winner-take-all primary. Instead, he is focusing on upcoming caucuses in Nevada, Colorado and Minnesota in a bid to win more delegates so he can wield influence at the Republican convention in August.
The new CNN-Time-ORC International poll was conducted Sunday through Tuesday, mostly before and partially after Monday night's Republican presidential debate in Tampa, where Romney aggressively attacked Gingrich.
On Sunday, the day after Gingrich won big in South Carolina, he was at 38% in Florida, with Romney at 36%, Santorum at 11% and Paul at 8%. Looking only at Monday and Tuesday's results, Romney was at 38%, Gingrich 29%, Santorum at 11% and Paul at 9%.
An American Research Group poll published Wednesday and conducted entirely after Gingrich's South Carolina win gave Romney a 7-point margin over Gingrich among likely GOP primary voters.
But a Quinnipiac University poll released hours earlier had the pair virtually even, with Romney attracting 36% of votes from likely GOP voters to 34% for Gingrich. That poll, which was conducted partially before and after the South Carolina vote -- but before the Monday debate -- showed a surge in support for Gingrich following his Palmetto State victory.
Florida, where 1.95 million people voted in the GOP primary in 2008, is a big prize for the Republican hopefuls.
The Florida Department of State said Wednesday that nearly 400,000 people have already voted under a system that includes absentee ballots and early voting that started Saturday.
According to the state, 127,389 early votes have been cast while 259,691 absentee ballots have been returned so far. More than 520,000 people requested absentee ballots.
Romney, Gingrich and Santorum hoped to woo Latino voters by taking part in the Univision forum in Miami.
Gingrich was the first to be quizzed by Univision anchor Jorge Ramos, discussing character and perceived hypocrisy concerning his personal life in the past.
Asked about his role in the impeachment proceedings against President Bill Clinton in the 1990s when he also was engaged in an extramarital affair, Gingrich rejected the suggestion he had been a hypocrite.
"I didn't do the same thing. I have never lied under oath. I have never committed perjury. I have never been involved in a felony. He was," Gingrich said, referring to the allegations of perjury involving the Paula Jones sexual harassment civil case and Clinton's affair with Monica Lewinsky.
Gingrich also expressed a willingness to compromise with Democrats, saying he would act like former President Ronald Reagan in that regard.
"I do follow his example, which was to be as conservative as possible and on occasion grudgingly give in to the left if there was nothing else to do," Gingrich said "If you can get 80% of what you want, take it, and come back later for more, but don't say it's 100% or nothing, because then you get nothing done."
CNN's Laura Smith-Spark, Tom Cohen, Dana Bash, Gregory Wallace, Shawna Shepherd and Paul Steinhauser contributed to this report.