The debate is the final one scheduled by the Republican National Committee. In less than six weeks’ time, on Jan. 15, Iowa will hold its caucuses and, a week later, New Hampshire voters will go to the polls in their primary -- as the 2024 presidential race gets underway.

Candidates are eyeing these two January contests to get some liftoff with the public before Nevada and South Carolina hold their own contests in February, followed by Super Tuesday on March 5, when more than 10 states hold primary elections.

By then, just three months from now, a clear front-runner for the parties' eventual nominations very well could have emerged.

-ABC News’ Chris Boccia

I’m Katie Sanders, the editor-in-chief of PolitiFact. I’ll be chiming in with fact-checks throughout the debate, but know that I’m one of approximately 20 PolitiFact journalists watching for candidates’ exaggerations and false attacks -- the kind of moments that make you go “really?!” when you hear them.

We’re coming in fresh from covering last Thursday's Gavin Newsom-Ron DeSantis debate on Fox News. For this one, it's totally fine by me if the candidates want to stick to claims we've already covered. But we're ready for surprises.

-Katie Sanders, PolitiFact

Trump is skipping the chance to debate for the fourth time.

Instead of joining his challengers in Tuscaloosa, the former president will participate in a fundraiser in Hallandale Beach, Florida, for his campaign and his Save America PAC.

Trump offered some counterprogramming on Tuesday night with a town hall hosted by Fox News' Sean Hannity, during which he raised alarms by referring to himself as a "dictator" if elected, but only on "day one," saying his priorities would be closing the border and drilling.

-ABC News' Alexandra Hutzler

Can anyone take down Haley? According to 538’s polling with The Washington Post and Ipsos, Republican primary voters have responded favorably to each of Haley’s first three debate performances, and it’s probably not a coincidence that she’s been rising in the polls at the same time. But that could put a target on her back on Wednesday -- and it’s possible that her momentum will stall if she’s perceived to have a bad performance.

Will anyone go after Trump? So far, the debates have mostly consisted of the candidates on stage attacking each other. But that’s an odd strategy considering that their biggest obstacle to the nomination is Trump. In fact, he’s above 50% in 538’s national polling average -- meaning that even if another candidate consolidates all of the non-Trump vote, Trump would still be ahead. That means that someone is going to have to peel support away from Trump in order to win the nomination -- and one way to do that is to attack him in the debates.

Who will perform best on the economy and immigration? According to the latest 538/Washington Post/Ipsos poll, 52% of likely Republican voters said getting inflation or costs under control was one of the top three issues in determining their primary vote; 41% said controlling immigration was one of their top three issues. These will probably be the most important segments to watch at the debate then: If a candidate really aces a question on inflation or immigration, that could go a long way.

Will anyone watch? The ratings have been falling with every debate: While the August faceoff garnered 12.8 million viewers, the September one got 9.5 million and the November one got only 7.5 million. And only 26% of the respondents to our 538/Washington Post/Ipsos poll said they were very likely or absolutely certain to watch the fourth debate. Obviously, the fewer people who watch the debate, the less anything that happens on stage will matter.

-Analysis by Nathaniel Rakich of 538

At the beginning of the year, DeSantis was the clear runner-up in the Republican presidential primary field: He was averaging above 30% in national polls, only about 10 points behind Trump. But DeSantis’ star has fallen the more voters have gotten to know him, it seems, and another candidate is now on the verge of overtaking him as the most viable Trump alternative: Haley.

As of Tuesday, Haley was at 11% in 538’s national polling average of the Republican primary -- just 2 points behind DeSantis for second place. And she’s doing even better in early primary states. She’s polling at 15% in Iowa, and she’s comfortably in second place in New Hampshire (19%) and South Carolina (21%).

She also recently secured the endorsement of Americans for Prosperity Action, a conservative group affiliated with Republican megadonor Charles Koch that is known for its sophisticated political operation.

Why has Haley been on the upswing? The simplest explanation is these debates. On the day of the first debate, she was averaging just 3% in national polls. But according to a 538/Washington Post/Ipsos poll conducted both before and after that debate, Republicans who watched said Haley was one of the strongest performers, and the share who said they were considering voting for her shot up by 17 points.

Republican debate watchers also rated Haley as the second-best performer in the second debate and the strongest performer in the third debate. Probably not by coincidence, her polling numbers have been steadily increasing ever since.

Of course, Haley fans shouldn’t get too giddy. She (and DeSantis) are still far behind Trump both nationally and in the early primary states. Even if Haley does overtake DeSantis and winds up being the last non-Trump Republican standing in the primary, it won’t matter if Trump is winning every state by double digits.

-Analysis by Nathaniel Rakich of 538