Donald Trump, president and chief executive of Trump Organization Inc. and 2016 Republican presidential candidate, left, shakes hands with Senator Ted Cruz, a Republican from Texas and 2016 presidential candidate, during the Republican presidential candidate debate at the North Charleston Coliseum in North Charleston, South Carolina, U.S., on Thursday, Jan. 14, 2016. The sixth Republican debate comes at a time with less than three weeks before Iowa caucus-goers cast the first votes of the 2016 presidential election on February 1. Photographer: Andrew Harrer/Bloomberg via Getty Images