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GOP debate: Five things to watch for

GOP presidential debate in South Carolina
Republican presidential candidates, former Pennsylvania Sen. Rick Santorum, former Massachusetts Gov. Mitt Romney, former House Speaker Newt Gingrich, Rep. Ron Paul, R-Texas, during the Republican presidential candidate debate at the North Charleston Coliseum in Charleston, S.C., Jan. 19, 2012. AP Photo/David Goldman

The four remaining Republican presidential contenders will take the stage for their 19th -- that's right, 19th -- debate Thursday evening. Hosted by CNN, the Republican Party of Florida and the Hispanic Leadership Network, tonight's debate is the last before the Florida primary on Tuesday. The debate could give either Mitt Romney or Newt Gingrich the momentum they need to clinch the Florida contest.

Here's what to watch for in tonight's debate:

Who goes on the attack?

In the debates leading up to the South Carolina primary, Gingrich gave feisty performances -- going after the media as well as his opponents -- that helped him win the Palmetto state primary.

But in a debate Monday night in Florida, perhaps because of his new frontrunner status, Gingrich took a more subdued tone while Romney got more aggressive.

Based on today's events on the campaign trail, both of the frontrunners may come out guns blazing in tonight's debate.

Gingrich was clearly angry at his GOP rival today, accusing him of everything from lying and hypocrisy to treating his competitors like they are "stupid."

Romney saved his criticism today for President Obama, but his surrogates were on the war path. Romney supporters like Reps. Jason Chaffetz, R-Utah, and Connie Mack, R-Fla., actually went to Gingrich events, where they slammed the former speaker to the press and even had some confrontational moments with the Gingrich campaign.

(Watch Chaffetz spar with Gingrich campaign spokesman R.C. Hammond in the video above.)

Will the audience get rowdy?

A large part of Gingrich's success in previous debates was the overwhelmingly positive response he received from the crowd. In Monday's debate, the audience was barred from clapping, which clearly hurt Gingrich.

In this debate, CNN is allowing applause from the audience. "But I don't want to see any craziness," CNN's Wolf Blitzer said in a radio interview today. "I want the audience to be respectful of these four candidates."

The Gingrich campaign has now admitted that the confrontation with CNN debate moderator John King that won Gingrich a standing ovation in the January 26 debate actually included some inaccurate claims from Gingrich.

Still, the candidate hinted on the campaign trail that he's not done targeting debate moderators. In Jacksonville today, he said he would reject debates in the general election in which only reporters decide on the questions and format -- he said he's "had enough of newsmen deciding what the questions ought to be."

Romney is also hoping for a little audience love tonight. In Jacksonville today, he told supporters he'd love to hear them cheer in the debate and told them if they don't have tickets they should "storm in."

Will the focus fall on Florida housing or lunar colonies?

The housing market and the space industry are huge issues in Florida -- and they've come into play in the primary in interesting ways recently.

Both candidates have spoken at length on the campaign trail about Florida's hard hit housing industry -- as of December 2011, 1 of every 360 homes in Florida were in foreclosure, ranking it 5th in the country in terms of foreclosure rates.

Gingrich today used that fact to slam Romney. Alluding to a report from the liberal site ThinkProgress, Gingrich said, "Here's a guy a who owns Freddie Mac and Fannie Mae stock. He owns a Goldman Sachs subsidiary that forecloses on Floridians."

Florida's Space Coast is also a hot economic issue. When NASA ended the U.S. shuttle program in 2011, about 9,000 workers were out of a job. Appealing to that sector this week, Gingrich promised to have a permanent U.S. base on the moon by the end of his second term as president.

Romney could seize that promise to mock Gingrich, as he did in a December debate. When asked where he differs with Gingrich, Romney prompted the audience to laugh by responding, "We can start with his idea to have a lunar colony that would mine minerals from the moon."

Can Santorum break through?

Former Sen. Rick Santorum needs a big moment in tonight's debate to tamp down the notion that this has become a two-man race. The candidate is currently in third place in the Sunshine state -- though that may count as last, since Rep. Ron Paul has opted to essentially skip campaigning there in favor of focusing on caucus states.

Santorum said on Thursday he plans to compete full force in Florida's primary Tuesday, but may soon turn his attention to less expensive primary states.

"We have committed pretty much every campaign day, with the exception of one to get my tax returns, to the state of Florida," he said. "Look, we're going to run every race. We are going to run in every state that we possibly can and get out there and we've got a strong message."

Will the ghost of Reagan return?

Gingrich has taken to calling himself a "Reagan Republican," but the Romney camp and other conservatives have pushed back against that characterization.

For instance, Elliott Abrams, who served as an assistant secretary of state in the Reagan administration, wrote in the National Review today that Gingrich's claims of having "worked with President Reagan to change things in Washington" - among others - are "misleading at best."

On the campaign trail today, Gingrich defended his "Reagan" values and said he found the pushback from the Romney campaign "infuriating."

The sparring reflects the discomfort establishment Republicans have over Gingrich's candidacy, and that friction leaves Gingrich vulnerable. The Gingrich campaign today has been responding aggressively to the criticism.

With reporting from CBS News/National Journal reporters Sarah Boxer and Sarah Huisenga.