Haley going after Ramaswamy was a recurring theme in the first debate. They were the standout candidates in our polling last time and there was a lot of speculation about Ramaswamy moving up in the polls — perhaps even surpassing DeSantis. But since August, Ramaswamy has actually lost support, to the point where Haley passed him in our polling average today. It makes sense that they're trading blows again; this seems to be a successful strategy for Haley, and Ramaswamy can't help but take the bait.
-Analysis by G. Elliott Morris of 538

The candidates are discussing support for Ukraine. About half (49 percent) of Republicans and Republican-leaning independents say that vital U.S. interests are not really at stake in the war in Ukraine, according to an August Echelon Insights survey. Thirty-seven percent disagree, saying that if Russia wins, vital U.S. interests and values are threatened. Fourteen percent are unsure.
—Analysis by 538

For those keeping score at hope, Christie, Pence, Scott and now Haley have all gotten into shouting matches with Ramaswamy at these debates.

—Analysis by Nathaniel Rakich of 538

DeSantis finally gets a little momentum. His "they don't care" repetition is the most impassioned he's been all night (or in either debate). But whatever applause he might have got was cut short the conversation moving on a discussion about NATO and another Scott/Ramaswamy spat.
-Jacob Rubashkin, 538 contributor

Trump maintains a lead of 27 percentage points over Haley, his nearest competitor in South Carolina, according to polls conducted since the first debate. Haley’s average support has grown by 9 points since the first debate, while DeSantis and Scott have fallen.

According to a September survey from Beacon Research/Shaw & Co. Research/Fox Business, 69 percent of likely South Carolina Republican primary voters say they support their first-choice candidate strongly, while 28 percent say they support them only somewhat. Among those that list Trump as their first choice, 86 percent say they support him strongly, while the second-place candidate, Haley, has only 57 percent saying the same.

In a September survey by Monmouth University/The Washington Post, South Carolina primary voters are split on whether the Republican Party should nominate a candidate who agrees with them on major issues (51 percent) or one who can beat Biden (45 percent). Among voters who say they are very or somewhat conservative, selecting a candidate who can beat Joe Biden is more important by a margin of 7 and 11 percentage points, respectively. Voters who say they are moderate or liberal prefer a candidate who agrees with them on major issues by 31 percentage points.

—Analysis by 538