DeSantis wouldn’t directly answer when the moderators asked him if he would sign a national abortion ban, and Pence pounced. He comes from the social conservative wing of the party, and supports a national ban. This isn’t the first time Pence has criticized DeSantis for not being conservative enough on abortion, either.
-Analysis by Nathaniel Rakich of FiveThirtyEight

Haley reiterated her calls for "compassion" when the country debates abortion, though she declined to state whether she would support a federal ban on the procedure.

Haley noted the uphill climb to a federal ban, referencing the 60-vote filibuster in the Senate, but said she would oppose late-term abortions and punishments for women who receive abortions.

"Can't we all agree that we should ban late term abortions? Can't we all agree that we should encourage adoptions? Can't we all agree that doctors and nurses who don't believe in abortion shouldn't have to perform them? Can't we all agree that contraception should be available? And can't we all agree that we are not going to put a woman in jail or give her the death penalty if she gets an abortion? Let's treat this like the like the respectful issue that it is," she said.

-ABC News' Tal Axelrod

The candidates are now debating abortion, which has obviously been a hot-button issue lately, but it’s actually not super important to Republican primary voters right now. According to our FiveThirtyEight/Washington Post/Ipsos poll, only 6 percent of Republicans identified limiting abortion as one of their top three issues.
-Analysis by Nathaniel Rakich of FiveThirtyEight

In the commercial break we get an ad targeting pro-Ukraine Republicans from Defending Democracy Together, a PAC led by a group of anti-Trump conservatives who have been very active in politics since 2017. In a poll from the Pew Research Center in June 44 percent of Republicans said the US was giving too much aid to Ukraine. I'm not sure how much this ad is going to register; Ukraine and national defense barely register in polls of Americans' most important problem these days. I think it says more about the divide in the party over Trump — who hasn't been mentioned in the debate at all so far.
-Analysis by G Elliott Morris of FiveThirtyEight

Recent election cycles have shown how debates can substantially alter a candidate’s trajectory. The debates won’t always do this, of course, and early primary polls remain relatively predictive of who will end up winning a party’s nomination. However, a candidate can earn a real polling bounce from a debate — or fall into a valley.

Primary polls are inherently more volatile than general election polls. In a general election, most voters already lean toward one party, so only a small part of the electorate is likely to shift its views over the course of a campaign. But in a primary, voters in one party may be open to multiple candidates because most contenders will share similar views on a number of issues. As a result, exposure to an unfamiliar candidate could prompt voters to begin considering that contender, while a strong or weak performance by a candidate they do know could make them look elsewhere.

For example, early in the 2012 cycle, Texas Gov. Rick Perry appeared to be now-Sen. Mitt Romney’s most serious opponent for the Republican nomination. But in a September 2011 debate, Perry defended a Texas policy that gave undocumented immigrants access to in-state college tuition. The backlash from the GOP base came swiftly, as Perry fell out of contention in the polls, well before a later debate in which he — oops — forgot the name of the third of three federal agencies that he aimed to dismantle as president. Four years later, former tech executive Carly Fiorina had very little support early in the 2016 Republican race, but in August 2015 she stood out in an “undercard” debate. Her polling numbers improved and she made the main stage in subsequent debates, giving her a platform that eventually led Texas Sen. Ted Cruz to make her his vice presidential pick in a last-ditch attempt to rally support against Trump in the 2016 primary.

-Analysis by Geoffrey Skelley of FiveThirtyEight