Republican presidential candidates (L-R) Donald Trump, Sen. Ted Cruz (R-TX), Ben Carson and Jeb Bush on January 14, 2016 in North Charleston, South Carolina. (Andrew Burton/Getty Images)
Republican presidential candidates (L-R) Jeb Bush, Sen. Ted Cruz (R-TX) and New Jersey Governor Chris Christie GOP Debate January 28, 2016 in Des Moines, Iowa. (Scott Olson/Getty Images)
Republican presidential candidate Donald Trump waits to be introduced during a campaign event at the University of Iowa on January 26, 2016 in Iowa City, Iowa. (Joe Raedle/Getty Images)
Republican presidential candidate Sen. Marco Rubio (R-FL) speaks to guests during a rally on January 6, 2016 in Marshalltown, Iowa. (Scott Olson/Getty Images)
The podium before 2012 Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks at his final campaign rally at Verizon Wireless Arena on November 5, 2012 in Manchester, New Hampshire. (Justin Sullivan/Getty Images)