Republican Presidential Debate: 5 Things to Watch

— -- We're just hours away from the final Republican presidential debate before next Monday’s Iowa caucuses. But there's one major difference: Donald Trump won't be on the stage.

The Republican front-runner is waging war with Fox News and decided this week to boycott tonight's debate.

Seven other candidates will take to the main stage in Des Moines, Iowa, at 9 p.m. ET. Here are five things to watch for:

1. Without Trump, Ted Cruz will draw most of the fire

For the first time, Sen. Ted Cruz will be standing behind the center lectern, a spot that Trump has previously claimed.

With Trump and Cruz locked in a tight battle for the lead in Iowa, other candidates like Sen. Marco Rubio and Sen. Rand Paul will be attempting to boost their standing with Iowa voters.

Meanwhile, Cruz will be fending off attacks from his competitors on stage while also trying to win over any Trump voters who are still on the fence.

2. Will Trump's Absence Help or Hurt His Campaign?

“Most Trump supporters are set on supporting him so perhaps it’s not as crucial for him to be on stage,” Matt Strawn, the former chairman of the Iowa Republican Party, told ABC News.

But according to David Yepsen, the director of the Paul Simon Public Policy Institute at Southern Illinois University, Trump risks alienating undecided and first-time caucus goers.

It’s unlikely that Trump’s poll numbers will see a dramatic dip given how he’s fared so far in the race.

“If past performance is any indication of future coverage, we’ll all be talking about Trump Friday morning,” Strawn said.

3. A Change of Heart in the 11th Hour?

Although Trump is holding an event at the same time as the debate, is it possible for Trump to change his mind last minute? Yes.

Republican National Committee spokesman Sean Spicer said that “we can make the accommodations up to pretty close to go time” on MSNBC this morning.

But even if Trump is not on stage, expect the moderators and the other candidates to bring him up.

4. Will Rubio Get His Moment?

The Florida senator, who trails behind Cruz and Trump, will get the largest lift from Trump not being on stage.

Rubio told Megyn Kelly last night, “Obviously leaves more time for the rest of us.”

He'll take the stage on the heels of a brand new NBC/WSJ/Marist poll in Iowa showing him at 18 percent support - a strong third place and his highest backing in any poll in the state yet.

5. Candidates Make Their Final Pitches to Iowa Voters

Ben Carson, who was once neck-and-neck with Trump at the top of the polls, will also find Trump’s absence valuable given that he spoke the least at the last debate.

Chris Christie, John Kasich and Jeb Bush will also be trying to woo undecided voters in Iowa.

Carly Fiorina, Mike Huckabee, Rick Santorum and Jim Gilmore - who hit 1 percent in a recent national poll for the first time since August - will be competing in the undercard debate for a last-ditch effort to gain any meaningful support.

ABC News' Meridith McGraw contributed to this report.

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