The Republican presidential candidates have met 20 times to debate the issues. Here's a recap of each debate, from Ponzi schemes to $10,000 bets:
Click this photo to start the slideshow. Republican presidential candidates, from left to right: Texas Gov. Rick Perry; former Pennsylvania Sen. Rick Santorum; former Massachusetts Gov. Mitt Romney; former House Speaker Newt Gingrich; and Rep. Ron Paul, R-Texas; pose for a photo at the start of the South Carolina Republican presidential candidate debate in Myrtle Beach, S.C., Monday, Jan. 16, 2012. (AP Photo/Charles Dharapak)
(AP Photo/Charles Dharapak)
1. May 5 FOX News / South Carolina GOP Debate, Greenville, S.C.
Gary Johnson goes out on a limb with the South Carolina crowd, saying that immigration creates jobs and that the 11 million undocumented immigrants in the U.S.should be granted work visas.(AP Photo/Joe Burbank)
2. June 13 CNN / NH Union Leader / WMUR-TV Debate, Manchester, N.H.
One word: Obamneycare. Before the debate, Tim Pawlenty coined the term, amalgamating Obama and Romney, with the intention of comparing Mitt Romney's approach to health care in Massachusetts with the plan President Obama backed. Pawlenty backed off the criticism of Romney when they met face to face at the debate. Thereafter, his campaign sputtered.
3. Aug. 11 FOX News / Iowa GOP Straw Poll Debate, Ames, Iowa
In a debate that had Tim Pawlenty and Michele Bachmann sparring over whose record was more conservative, Mitt Romney floated above the fray, and Newt Gingrich pounced on the media for playing "Mickey Mouse games."(Chet Susslin)
4. Sept. 7 Reagan Library Debate, Simi Valley, Calif.
Rick Perry debuts at the debate scene and played equal parts front-runner and Texas outlaw as he set his sights on Social Security: “It is a Ponzi scheme to tell our kids that are 25 or 30 years old today, 'you're paying into a program that's going to be there,'" Perry said.(AP Photo/Jae C. Hong)
5. Sept. 12 CNN Tea Party Debate, Tampa, Fla.
Rick Perry vs. Mitt Romney on Social Security: Romney insisted that Perry was scaring Americans by calling the program a Ponzi scheme; Perry shot back that Romney had called the program criminal in his book, winning over the tea party crowd at the debate.(AP Photo/Mike Carlson)
6. Sept. 22 Fox Florida Debate, Orlando, Fla.
Gary Johnson of New Mexico quipped that his neighbor's two dogs "created more shovel-ready jobs" than President Obama.(AP Photo/Phelan M. Ebenhack, Pool))
7. Oct. 11 Bloomberg Debate, Hanover, N.H.
This was the first debate since New Jersey Gov. Chris Christie and former Alaska Gov. Sarah Palin said they wouldn't run. Rick Perry put in a poor performance, and Herman Cain's 9-9-9 plan won applause.(TONI SANDYS, POOL/AP)
8. Oct. 18 Western Leadership Conference Debate in Las Vegas
Herman Cain surged and then fell back to earth as his rivals picked apart his 9-9-9 plan.(AP Photo/Chris Carlson)
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10. Nov. 12 CBS/NJ Debate, Spartanburg, S.C.
Mitt Romney, who took a hard-line position on Iran and criticized President Obama's foreign policies, was the favorite among National Journal's Insiders. “Romney looked steady and up to the task at the commander-in-chief debate tonight," said one Insider.(Richard Shiro/AP)
11. Nov. 22 CNN Foreign Policy Debate, Washington, D.C.
National Journal Editorial Director Ronald Brownstein perhaps put it best: "Newt Gingrich, freshly minted as the GOP front-runner in a CNN/ORC poll released Monday, radiated Olympian self-assurance in Tuesday night’s debate."
13. Dec. 15 Fox Debate, Sioux City, Iowa
The candidates came to a hawkish consensus on foreign policy, except for Texas Rep. Ron Paul, who made a different argument. “Why do we have to bomb so many countries? Why are we--why do we have 900 bases in 130 countries and we're totally bankrupt? How do you rebuild a military when we have no money? How are we going to take care of the people," Paul asked.(AP Photo/Chris Carlson)
15. Jan. 8 NBC News/Facebook, Concord, N.H.
In the last debate before the New Hampshire primary, Newt Gingrich jabbed at Mitt Romney who sought to portray himself a businessman and private citizen. "You've been running consistently for years and years and years. So this idea that suddenly citizenship showed up in your mind -- just level with the American people," Gingrich said.(Elise Amendola/AP)
16. Jan. 16 Fox News Debate, Myrtle Beach, S.C.
The crowd comes to life in the Palmetto State: For once, it was only Ron Paul's supporters who had cause to cheer boisterously.(AP Photo/Charles Dharapak)
17. Jan. 19 CNN Debate, Charleston, S.C.
Newt Gingrich pounded the media right off the bat: CNN moderator John King asked Gingrich about an interview with his second ex-wife, Marianne, in which she told ABC that he had asked for an "open marriage." "I am tired of the elite media protecting Barack Obama by attacking Republicans," he insisted to loud applause.(David Goldman/AP)
18. Jan. 23 NBC News/National Journal/ Tampa Bay Times
Crickets: That was the sound that greeted Newt Gingrich's pointed retorts to Mitt Romney, at least compared to what he came to expect in debates.(AP Photo/Paul Sancya)