Republican presidential candidates (left-right) Bobby Jindal, Rick Perry, Rick Santorum, Carly Fiorina and George Pataki on stage during the first "kid's table" debate last month. John Minchillo/AP hide caption

itoggle caption John Minchillo/AP

Republican presidential candidates Donald Trump (right) and Wisconsin Gov. Scott Walker speak together during a commercial break at the first Republican presidential debate in Cleveland on Thursday. Trump's remarks about Fox News debate moderator Megyn Kelly have triggered a firestorm. Andrew Harnik/AP hide caption

itoggle caption Andrew Harnik/AP

Newt Gingrich greets supporters during a rally at Wings Plus in Coral Springs, Fla., on Jan. 25. The GOP candidates meet in Jacksonville Thursday night for a final debate before Tuesday's primary. Carline Jean/MCT/Landov hide caption

itoggle caption Carline Jean/MCT/Landov

Former Massachusetts Gov. Mitt Romney (left) and Texas Gov. Rick Perry got into a heated exchange about immigration during Tuesday's GOP presidential debate in Las Vegas.

Ethan Miller/Getty Images hide caption

itoggle caption Ethan Miller/Getty Images