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

Trump maintains a lead of 25 percentage points over his nearest competitor in Iowa, according to the latest polls.

DeSantis and Scott are both polling higher in Iowa than they are nationally, according to our polling average. Trump is polling about 10 points lower in Iowa than in national polls.

According to a July poll from J.L. Partners/DailyMail.com, only 51 percent of Iowa Republicans said their mind was made up. Forty-three percent said they could still be persuaded to support another candidate. Voters who said they plan to vote for Trump were the most likely to say their mind is made up, with 80 percent saying so compared with 37 percent of those who said they plan to vote for DeSantis and 11 percent of those who said they plan to vote for Scott.

Scott and DeSantis have the highest net favorability among Iowa Republican voters. Pence, Christie and Hutchinson are underwater.

In an early state poll from the Manhattan Institute conducted in July, Iowa Republicans are split on whether electability is important. Forty-six percent of Iowa Republican voters say that it is most important for Republican candidates to win elections and be in power, even if that means compromising or moderating their positions, while 45 percent said it is most important for candidates to stay true to their principles, even if that means losing elections.

Iowa Republicans also think that skipping primary debates shows weakness more than strength, according to a July Fox Business/Beacon Research/Shaw & Co. Research survey. Fifty-nine percent of Republicans said skipping the debate shows weakness, while 27 percent said it shows strength.

-Analysis by FiveThirtyEight