Rudy Giuliani

Despite a poor showing in his 2008 presidential bid, the former New York City mayor says he's considering another run in 2012. His social and fiscal moderation could be a liability in the GOP primaries, but if the debate turns to national security Giuliani could get a major boost thanks to his widely lauded performance in the wake of the Sept. 11 terrorist attacks and tough-on-crime reputation.

Credit: AP Photo/Paul Sancya