Jeb Bush, former Governor of Florida and 2016 Republican presidential candidate, listens to an audience question during a town hall event hosted by CNN at the University of South Carolina in Columbia, South Carolina, U.S., on Wednesday, Feb. 17, 2016. Donald Trump remains the front-runner in South Carolina, where Republican voters head to the polls on Saturday. According to a survey released Monday by Democratic pollster Public Policy Polling, Trump holds a 17-point lead over Senators Marco Rubio and Ted Cruz, who are tied for second place. Photographer: Daniel Acker/Bloomberg via Getty Images

Jeb Bush, former Governor of Florida and 2016 Republican presidential candidate, listens to an audience question during a town hall event hosted by CNN at the University of South Carolina in Columbia, South Carolina, U.S., on Wednesday, Feb. 17, 2016. Donald Trump remains the front-runner in South Carolina, where Republican voters head to the polls on Saturday. According to a survey released Monday by Democratic pollster Public Policy Polling, Trump holds a 17-point lead over Senators Marco Rubio and Ted Cruz, who are tied for second place. Photographer: Daniel Acker/Bloomberg via Getty Images