With the Iowa caucuses only days away, Republicans will have one last chance Thursday to debate before Iowans gather and the race for the nomination kicks into high gear. But front-runner Donald Trump will not be center stage after declining to participate in the event.

The candidates will face off in Des Moines Thursday evening during the debate hosted by Fox News and Google. Texas Sen. Ted Cruz, Florida Sen. Marco Rubio, retired neurosurgeon Dr. Ben Carson, former Florida Gov. Jeb Bush, New Jersey Gov. Chris Christie, Ohio Gov. John Kasich and Kentucky Sen. Rand Paul will headline the main debate at 8 p.m. local time (9 p.m. EST).

Fox anchors Bret Baier, Megyn Kelly and Chris Wallace, who moderated the August Fox debate, are returning to ask questions and keep candidates in check during the two-hour primetime debate.

Trump and Kelly have a history of unpleasant exchanges, with the businessman accusing her of having “blood coming out of her wherever” after she questioned him in the August debate over past remarks about women. Ahead of Thursday’s debate, Trump again went on the offensive against Kelly, calling her biased and a "third-rate reporter" before ultimately deciding not to participate, accusing Fox of profiting from ads ahead of the event.

“Fox is playing games,” Trump said. “They can’t toy with me like they toy with everybody else. Let them have the debate. Let’s see how they do with the ratings.”

Since the last debate, candidates have picked up more endorsements, with former Alaska Gov. Sarah Palin throwing her support behind Trump while the Des Moines Register wrote an editorial in support of Rubio.

While former Hewlett-Packard boss Carly Fiorina, former Arkansas Gov. Mike Huckabee, former Pennsylvania Sen. Rick Santorum and former Virginia Gov. Jim Gilmore did not meet the criteria of the primetime debate, they will participate in the undercard event at 7 p.m. EST at the Iowa Events Center, with Fox anchors Bill Hemmer and Martha MacCallum moderating.

Both debates will be available on Fox News, Fox News radio and online through FoxNews.com. The next Republican debate will take place Feb. 6 in Manchester, New Hampshire, three days before the primary there.