What 538 will be watching for
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