Nine candidates will appear on stage Tuesday night in Las Vegas for the fifth and final Republican presidential primary debate of 2015.

Reflecting recent poll numbers, Donald Trump will take center stage, joined on either side by Texas Sen. Ted Cruz and Dr. Ben Carson. Filling out the flanks are Florida Sen. Marco Rubio, former Florida Gov. Jeb Bush, former Hewlett-Packard CEO Carly Fiorina, Kentucky Sen. Rand Paul, Ohio Gov. John Kasich and New Jersey Gov. Chris Christie, who finds himself back in the primetime lineup after failing to qualify for the previous primetime debate, hosted by Fox Business.

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Tuesday’s debate, which begins at 8.30 p.m. EST and is co-hosted by CNN and Salem Media, is the first to use poll numbers in early voting states as a means for qualification. Candidates needed to receive an average of at least 3.5 percent in national polls, or 4 percent in Iowa or New Hampshire, to make it onto the stage.

This novelty allowed Christie to return to the prime-time stage — and Paul to remain on it — as neither candidates are polling nationally as well as they are in Iowa and New Hampshire.

Former Pennsylvania Sen. Rick Santorum, former Arkansas Gov. Mike Huckabee, South Carolina Sen. Lindsey Graham and former New York Gov. George Pataki all failed to qualify for the prime-time debate and will face off in an “undercard” debate at 6 p.m. EST.

Tuesday’s prime-time debate will be moderated by Wolf Blitzer, who will be joined by CNN’s Dana Bash and Hugh Hewitt.

Tuesday’s prime-time debate will be moderated by Wolf Blitzer, who will be joined by CNN’s Dana Bash and radio talk show host Hugh Hewitt. The focus will be national security, and in light of recent terror attacks in Europe and America and Trump’s controversial Muslim immigration ban proposal, there will be much to discuss.

Cruz and Paul will have to defend their more libertarian views on intelligence gathering and counterterrorism efforts against guaranteed attacks from Rubio and Christie, while Trump is likely to come under fire from all sides, except perhaps Cruz, for his Muslim immigration ban. Trump may need to prove he has a serious plan for defeating ISIS, not just keeping them out of the country.

The debate is being held at The Venetian, a luxury hotel and casino owned and operated by billionaire GOP donor Sheldon Adelson’s Las Vegas Sands Corp. Although Adelson has yet to officially endorse a candidate, he met with Rubio in October and is said to be a fan of the Florida senator. Adelson and his wife have given donations to Rubio’s joint fundraising account, according to The Hill.