Ramaswamy and Haley traded shots on his Israel and Russia-Ukraine views, with Ramaswamy interrupting Haley and claiming she has been saying misleading things about his proposals on Israel. Ramaswamy has called for winding down aid to Israel after integrating the country more into the region.

"I wish you well on your future career on the boards of Lockheed and Raytheon,” Ramaswamy quipped, referring to the aerospace and defense companies.

Haley struck back: "You have no foreign policy experience and it shows," she said -- and was met with cheers and applause from the audience.

-ABC News’ Abby Cruz

Trump wasted no time attacking other Republican candidates during his pre-taped interview with former Fox News host Carlson.

"I'm saying, do I sit there for an hour or two hours, whatever it's going to be and get harassed by people that shouldn't even be running for president?" Trump said.

The 46-minute interview -- released on Carlson's X account as the GOP debate got underway -- is being seen among the campaigns as an attempt to counter-program the first debate among 2024 Republican presidential candidates on Fox News.

Read more about the interview here.

-ABC News' Lalee Ibssa , Soo Rin Kim and Meredith Deliso

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

In the aftermath of a debate, it can be hard to figure out the actual impact of a viral moment or heated exchange. Here are some data-driven approaches that can help cut through the noise:

First, ignore “instant polls” that ask questions only among people who watched the debate. That group is not likely to represent the feelings of the broader population. Instead, look for post-debate polls — (like ours with Ipsos and the Washington Post) — that ask questions among the same group of Americans both pre- and post-debate.

Second, in the days following the debate, look at data that captures attention to candidates, such as trends in search results or media coverage, to determine which candidate made the biggest splash. Media attention is crucial for candidates who aren’t well known to gain traction in the polls and with donors.

Finally, look for changes in horse-race polls in the week or two after the debate. There is a lot of noise in primary polls (especially this time around) and it can take some time for changes in public opinion to be reflected in our polling average.

The big thing to remember is that what’s important to journalists and television pundits may not be what’s important to the public, and we have to wait for pollsters to ask them how they feel.

-Analysis by G. Elliott Morris of FiveThirtyEight