Tune in to CNN on Thursday night at 8 ET as the GOP candidates debate the issues live from Jacksonville, Florida, just days before the state's primary. Watch it all live on CNN, CNN.com/Live and CNN's mobile apps.
(CNN) -- After Saturday's South Carolina primary shook up the Republican presidential race, the four major candidates matched up on Monday in the first of two debates in Florida, which votes next on January 31. Here are five things we learned:
A new twist on "Newt Romney"
Newt Gingrich got a taste of the one-on-one debate he's proposed having with Mitt Romney Monday night, when the former Massachusetts governor launched an unrelenting attack against Gingrich and kept at it for much of the evening.
Continuing the assault he had launched since losing the South Carolina primary to Gingrich on Saturday, Romney went after the former House speaker in a big way in Tampa, calling him an "influence peddler" and mocking Gingrich for saying he advised troubled mortgage giant Freddie Mac as "an historian."
He continued to tie Gingrich's consulting work to the foreclosure crisis gripping Florida.
"You could have spoken out in a way to say these guys are wrong, this needs to end," he told Gingrich. "But instead, you were being paid by them. You were making over $1 million at the same time people in Florida were being hurt by millions of dollars."
Romney senior adviser Stuart Stevens denied his candidate had shifted from last week's regret of attacking his opponents but that he is "a very aggressive individual" who took "a certain delight" in taking on the speaker's "preposterous statements."
So effective was Romney's attack that it raised questions about whether Gingrich had parried strongly enough to hold his own on the issue with his on-stage rival.
In a sign the Romney campaign would keep up the pressure, senior strategist Eric Fehrnstrom pointed to a statement Gingrich made in the debate that he had hired an "expert on lobbying law" to advise his Washington firm on "the bright line between what you can do as a citizen and what you can do as a lobbyist."
After the debate Fehrnstrom said Gingrich should follow up on his offer to make that expert available to testify about the training.
"He's got a lobbying expert who apparently went into Gingrich's lobbying firm and explained to them how they could exploit loopholes in the law so that their activities couldn't fairly be described lobbying," Fehrnstrom said. "I'd like to hear his testimony."
Hitting the mute button
During the last GOP debate in Charleston, South Carolina, a rowdy audience seemed to embolden the four candidates to go after each other more aggressively and even push moderator John King to direct at least one more question towards Ron Paul than he had planned.
At the start of Monday's debate, moderator Brian Williams asked all the invited guests to "withhold their applause, any verbal reactions to what they hear onstage, so as to ensure this is about the four candidates here tonight and what they have to say."
At first this seemed like a modest change to the debate's rules, but it ended up having a significant effect. In a debate season where audiences have lustily cheered for their favorite candidates or in support of hard-line conservative principles, the absence of feedback was notable.
The silence was only broken on a few occasions and the candidates were unable to gauge the impact of their calculated applause lines, and when Romney and Gingrich engaged in a prolonged back-and-forth over the former speaker's consulting record with Freddie Mac, the audience's silence made it more difficult to divine who won the round.
Trying to shoulder into a two-man race
Rick Santorum has worked hard over the last several weeks to remind people that this isn't a two-man race and has consistently blamed the media for prematurely narrowing the field. He repeated that argument on Monday but had trouble making it stick.
"I think if you've learned anything about this election, that any type of prediction is going to be wrong," Santorum said. "The idea that this was a two-person race has been an idea that has been in fashion now for eight months, and it's been wrong about eight times."
Desperately in need of a game-changing performance, Santorum nonetheless seemed to take a backseat for much of the rest of the night. One of his two real moments on offense came as he was playing defense. When asked about his fellow Republicans' attacks on Romney's record at Bain Capital, Santorum pointed out that he hasn't gone after Romney. Then he went after Romney.
"My question to Gov. Romney and to Speaker Gingrich -- if you believe in capitalism that much, then why did you support the bailout of Wall Street?" Santorum asked.
Towards the end of the debate Santorum was given another chance to go after his opponents, this time on their past support for individual health insurance mandates. Calling mandates "the biggest issue" in this election, and something that is "crushing the economy, will crush it even further and crush freedom," Santorum quickly ran through his opponents' checkered past on the issue
"Gov. Romney's plan in Massachusetts was the basis for Obamacare," he began. "Speaker Gingrich for 20 years supported a federal individual mandate, something that [Florida Attorney General] Pam Bondi is now going to the Supreme Court saying is unconstitutional. Speaker Gingrich, for 20 years up until last year, supported an individual mandate, which is at the core of Obamacare."
Both of these attacks were well-launched, but neither seemed to land very effectively, and neither seemed to really have the potential for shaking up the current state of the race in Florida.
Ron Paul, who has already said he would not spend primary night in Florida, injected some humor and his trademark libertarian flavor to the proceedings -- but did not appear to change the political calculus in the fourth state to vote.
Asked again whether he thought he had a viable chance to win the Republican nomination, Paul pointed to his support among young adults, and again said he did not plan to run as a third-party candidate.
He addressed a previous statement about not imagining himself in the White House by reaffirming his commitment to the race.
"Unlike others, maybe they sit around and daydream about being in the White House," Paul said. "I just don't sit around daydreaming about it, but I'm in a race, I'm in a good race."
Practice makes perfect?
If at first you don't succeed, try, try again.
After a week of faltering answers, Mitt Romney managed to give a fluid response to questions about his tax returns -- just one day before he was scheduled to release them.
The multi-millionaire calmly answered a series of questions about his financial documentation, acknowledging his wealth but then pivoting to discuss overhauling America's tax policy.
He also seemed prepared for a question that seemed to fluster him in a previous matchup -- whether he would follow the lead of his father George Romney, a one-time presidential hopeful who made a point to release 12 years of his returns.
"I agree with my dad on a lot of things, but we also disagree," Romney said. "And going out with 12 years of returns is not something I'm going to do."
With practiced answers and by saying he would release his 2010 returns and estimated 2011 taxes on Tuesday, Romney hoped to defuse the issue that helped create a week of bad press in the run-up to the South Carolina primary. Whether he chose to release enough information quickly enough to quiet criticism from his own supporters and the media remains to be seen.
All politics is local
After primaries in three states that will play relatively minor roles in the 2012 general election, almost a third of Monday's debate focused on issues important to Florida, a swing state in November.
For one long portion of the debate, the questions ranged from the potential effects of another oil spill on the Sunshine State's vital tourism industry to the future of federal subsidies for Florida's sugar industry. Even the long-forgotten Terry Schiavo case came up.
One of the most interesting questions pertained to the potential hypocrisy of the candidates' choice to film campaign commercials and distribute fliers in Spanish despite their belief that English should be the nation's official language.
"I would have ballots in English, and I think you could have programs where virtually everybody would be able to read the ballots," Gingrich said, and nearly all of his rivals agreed.
"English is the language of this nation," Romney said. "People need to learn English to be able to be successful, to get great jobs. We don't want to have people limited in their capacity to achieve the American dream because they don't speak English."
In a state as big as Florida with such a diverse Republican electorate, candidates must appeal to voters on a variety of issues. While previous debates have taken on the issue of immigration, both Gingrich and Romney emphasized their willingness to sign a version of the DREAM Act that would help only undocumented immigrants serving in the military -- a slight divergence from the harder line expressed in past debates.
With Florida looming as a crucial state in 2012, whoever emerges as the eventual nominee will surely have to address many of these issues again, only now there are even more details of their positions on the record.
CNN Political Reporter Shannon Travis contributed to this report.