DeSantis expressed support for using the U.S. military to combat drug cartels across the border.

"The president of the United States has to use all available powers as commander in chief to protect our country and the people," DeSantis said.

"When they are coming across, yes we are going to use lethal force," he continued -- a line he's used repeatedly throughout the campaign.

Activists have pushed back that his plan is inhumane and illegal.

-ABC News' Alexandra Hutzler

Martha MacCallum just asked about what to do about migrants already in the United States. In a July poll by The New York Times/Siena College, 39 percent of likely Republican voters say that they supported a “comprehensive immigration reform bill that provides a pathway to citizenship for all undocumented immigrants” in the United States, while 57 percent opposed such a bill. Support was weakest among Trump supporters (29 percent) compared with DeSantis supporters (48 percent) and voters who say they will vote for another candidate (50 percent).
-Analysis by FiveThirtyEight

While many candidates onstage have sparred with each other -- including Haley and Ramaswamy swapping sharp words on foreign policy -- Scott has yet to engage with any of the other candidates.

Much of his remarks have almost word for word repeated elements from his campaign stump speech. When asked about China, which he has addressed in other appearances, he pivoted to speaking about the U.S. border.

-ABC News’ Gabriella Abdul-Hakim and Oren Oppenheim

Asked to raise their hand if they would not increase aid to Ukraine, DeSantis did so, saying that "Europe needs to step up. They need to step up and do their job."

He argued: "I would have Europe pull their weight. ... Our support should be contingent on them doing it.

DeSantis -- who had received backlash from some other politicians for seemingly backtracking on support for Ukraine -- pivoted to say that he wasn’t going to send troops overseas but rather down to the Southern border.

-ABC News' Hannah Demissie and Will McDuffie

Trump maintains a lead of 28 percentage points over his nearest competitor in South Carolina, according to the latest polls.

Haley and Scott, the two candidates from South Carolina, are both polling higher in South Carolina than they are nationally, according to our polling average. Trump is polling about 7 points lower in South Carolina than in national polls.

Only one pollster, the Manhattan Institute has tested the favorability of Republican candidates in South Carolina since July 1. That survey found Scott and DeSantis had the highest net favorability in the state (+56 and +55 percentage points, respectively), and Trump and Haley close behind (+39 and +33 points, respectively). Pence had a net favorability of +1 point, and Christie was underwater by -36 points.

Economic issues are most important to Republican primary voters in South Carolina, according to a July survey from Fox Business/Beacon Research/Shaw & Co. Research. Fifty-one percent of Republican voters said economic issues would be most important for deciding their vote. Twelve percent each said immigration issues, social issues and foreign policy were most important.

In an August survey by National Public Affairs, 40 percent of South Carolina Republican voters said that Trump wouldn’t lose their support even if he did not show up to the debate. Twelve percent said that they support Trump, but if he didn’t debate they would be open to or definitely supporting someone else, 32 percent said they wouldn’t vote for Trump regardless, 9 percent said they probably wouldn’t watch the debate anyway and 6 percent were unsure.

-Analysis by FiveThirtyEight