Republican candidates debate in South Carolina

Presidential candidates Jeb Bush, Ted Cruz and Donald Trump make their points at the GOP debate in Greenville, S.C.

John Kasich and Jeb Bush have an exchange during the GOP presidential debate.

John Kasich, Jeb Bush, Ted Cruz, Donald Trump, Marco Rubio and Ben Carson participate in the Republican debate in South Carolina.

Businessman Donald Trump speaks during the debate. He is the GOP front-runner heading into the critical South Carolina primary.

Donald Trump, center, looks and listens as fellow presidential candidates Ted Cruz, left, and Marco Rubio argue back and forth during the debate.

Republican presidential candidate Jeb Bush, a former governor of Florida, responds to businessman Donald Trump during the debate in Greenville, S.C.

Republican presidential candidate Ben Carson participates in the debate in Greenville, S.C.

Donald Trump speaks to U.S. Sen. Marco Rubio of Florida during the GOP debate in South Carolina.