Using military force in Mexico has become one of DeSantis's signature planks. In the past few months he's talked about sending special forces to confront the cartels, and didn't rule out firing missiles into Mexico either. It's a heavy-handed proposal that just a few years ago probably would have been major news but these days is pretty par for the course for more and more GOP officeholders.
-Jacob Rubashkin, 538 contributor

A plurality (31 percent) of Republican voters in a NewsNation poll from July said that drugs and substance abuse was the overall root cause of crime in their community. Twenty-three percent said the breakdown of the family unit was to blame, followed by 17 percent who listed underfunding of law enforcement. Systemic racism was the least mentioned issue, with just 3 percent of Republicans saying that it was the overall root cause of their community’s crime.
—Analysis by 538

Christie gets the first question out of the break on how to handle crime, and he made the case that he's the only person on stage whose done it as a former prosecutor. But he turned the question into an attack on Trump, calling out Trump for skipping out on the debate, saying that soon he'll be called "Donald Duck" for avoiding it. The thing is, Christie has essentially a 0 percent chance of winning the GOP nomination, so it's not especially interesting to hear him go after Trump. Earlier in the debate, DeSantis did echo an attack Christie made by hitting Trump for not being on stage to defend the former president's record on spending. More of those kind of dings from anyone besides Christie would be a development in this debate.

DeSantis stands by his decision to suspend two elected prosecutors in Florida, and says he'll bring civil rights cases (?) against local prosecutors as president.

-Jacob Rubashkin, 538 contributor

The second debate stage will look mostly like the first, as seven of the eight candidates who took part in the initial August debate qualified for tonight’s event. And just like the first debate, front-runner Trump has decided to skip the event, despite having the polls and donors to make it. To qualify, the RNC mandated that candidates have at least 3 percent support in two national polls, or at least 3 percent in one nationwide survey and two polls from separate early states, based on polls conducted since Aug. 1 that met the RNC’s criteria for inclusion. Candidates also had to attract at least 50,000 unique contributors, with at least 200 from 20 different states or territories.

The RNC raised the polling and donor standards for the second debate, which slightly winnowed the list of participants. The new rules raised the level of support candidates needed in qualifying polls from 1 percent to 3 percent, and the number of unique donors from 40,000 to 50,000. Six of the seven qualifying candidates had little trouble meeting these polling and donor thresholds. However, although Burgum had enough donors, he struggled to poll well enough nationally to qualify. It took until the Saturday before the debate for him to get the national poll at 3 percent he needed. Meanwhile, former Texas Rep. Will Hurd and former Arkansas Gov. Asa Hutchinson came up short of qualification, as Hurd lacked sufficient polls and only got to 50,000 donors on Monday, while Hutchinson didn’t have enough qualifying polls or donors.

—Analysis by Geoffrey Skelley of 538