Likely Republican voters are pretty split on "sending U.S. military forces to Mexico to fight drug cartels," according to our pre-debate 538/Washington Post/Ipsos poll. 44 percent support the proposed policy, compared with 46 percent who oppose.

—Analysis by Holly Fuong of 538

Some early moments in this debate have involved significant cross-talk and interruptions. Burgum's main two comments so far both came via him jumping in to speak without having been asked a question, which is something a low-polling candidate on the periphery of the stage (and race) might as well do with little to lose. Unlike in the first debate, there hasn't been as much of a push by the moderators to give a short rebuttal opportunity to candidates who were mentioned by another candidate, although multiple candidates have asked for that already.

—Analysis by Geoffrey Skelley of 538

The Trump administration built 52 miles of new primary border barriers — the first impediment people encounter if they’re trying to cross the southern border with Mexico, that can block access either for people on foot or for vehicles — where there were none before.

The administration built 458 total miles of primary and secondary border barriers, U.S. Customs and Border Protection data shows. The majority were replacements of smaller, dilapidated barriers.

The U.S.-Mexico border stretches for 2,000 miles across four states and a variety of terrain.
-Analysis by Aaron Sharockman, PolitiFact

Christie was just asked about his position on a pathway to citizenship for undocumented immigrants. 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 538

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