Haley spars with Republican rivals at 3rd primary debate as Trump still looms

Every candidate goes into a debate hoping for a viral moment or a game-changing performance. But unfortunately for them, that's usually just not how it works.

For instance, according to polling from 538, The Washington Post and Ipsos, the September GOP debate barely changed the minds of any Republican primary voters, and the August one succeeded only in giving Haley a modest boost. As a result, I'm skeptical that any candidate is going to have a breakout moment that will change the trajectory of their campaign.

Even if they have a strong performance and go up in the polls a little bit, like Haley did, they are still facing the reality that Trump is 40 points ahead of his closest competitor. And even if a candidate has a phenomenal debate performance in Miami and surges, say, 15 points in the polls (which would be pretty impressive!), they'd still be at least 25 points behind in the race overall.

-Analysis by Nathaniel Rakich of 538

During the debate, the five GOP candidates will be standing, from audience left to right: Christie, Haley, DeSantis, Ramaswamy and Scott.

Among the debate participants, DeSantis, in the center, is leading in the polls -- ranked second place nationally, according to 538's polling average. He's followed by Haley, Ramaswamy, Christie and Scott in the polls.

Trump continues to lead all of them by double digits.

To be eligible to participate in Wednesday's debate, a candidate must have at least 4% support in two national polls or at least 4% in one nationwide survey as well as two polls from separate early states, based on polls conducted since Sept. 1 that meet the Republican National Committee's criteria for inclusion.

-ABC News' Meredith Deliso

Perhaps the biggest subplot of the third Republican primary debate will be the interactions between DeSantis and Haley. They have emerged as the two main alternatives to Trump at this point. DeSantis, of course, started off his campaign as one of the front-runners, and while he has steadily declined in the polls over the last several months, he remains in second place nationally with 14% support, according to 538's national polling average. He's also in second place in the key early state of Iowa.

However, Haley has risen in the polls in recent months, and she's now in second place in two other key early states, New Hampshire and South Carolina.

With only five candidates qualifying for the debate, each of them will get more speaking time and the stage will feel more intimate. That could provide DeSantis and Haley with more opportunities to attack each other. According to polling from 538, The Washington Post and Ipsos, Republican voters have generally thought both DeSantis and Haley performed well in the first two debates.

But if one of them clearly bests the other on Wednesday night, that could be the differentiator that both of them are looking for.

-Analysis by Nathaniel Rakich of 538

The two-hour debate will feature four planned segments.

The "national security implications" of the Israel-Hamas and Russia-Ukraine wars will be a focus, along with domestic political issues, according to NBC News.

The moderators are also expected to reference campaign developments that NBC News reporting and polls show are of interest to voters, per organizers.

Candidates will have 90 seconds to answer each question, as well as 60 seconds to answer follow-up questions.

At the end, candidates will have 60 seconds to give a closing statement.

-ABC News' Meredith Deliso