Donald Trump, president and chief executive of Trump Organization Inc. and 2016 Republican presidential candidate, second left, speaks as 2016 Republican presidential candidates Ben Carson, retired neurosurgeon, from left, Senator Ted Cruz, a Republican from Texas, and Jeb Bush, former governor of Florida and 2016 Republican presidential candidate, listen during the Republican presidential candidate debate at The Venetian in Las Vegas, Nevada, U.S., on Tuesday, Dec. 15, 2015. With less than two months remaining before the Feb. 1 Iowa caucuses and the Feb. 9 New Hampshire primary, middle-of-the-pack candidates hoping for a late surge in the polls have little choice but to come out swinging in tonight's fifth Republican debate. Photographer: Ruth Fremson/Pool via Bloomberg