Trump still in lead going into GOP debate tonight

A smaller cast of Republican presidential candidates is ready to return to the main debate stage for one of the last high-profile opportunities for white house hopefuls to sway voters before the February 1st Iowa caucus.

Donald Trump speaks during a campaign event at the University of Northern Iowa in Cedar Falls, Iowa. (Photo by Joe Raedle/Getty Images)

The prime-time showdown in Charleston, South Carolina will highlight a race that has cleaved into two distinct, and increasingly heated contests.

After months of civility toward rival Ted Cruz, front-runner Donald Trump is aggressively targeting the Texan, saying the Canadian-born senator may be ineligible to be president.

Four other candidates, including Gov. Chris Christie, will be on stage fighting to become the mainstream Republican alternative.

Christie continues to lag in national polls, but he has been gaining ground in New Hampshire and Iowa.

The FOX Business Network will carry the debate tonight beginning with the undercard at 6 p.m. and the main stage at 9 p.m.