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

In anticipation of tonight’s debate, we again partnered with The Washington Post and Ipsos to ask likely Republican primary voters what they think about tonight’s debate participants and the candidate field in general.

The 5,002 likely Republican primary voters we polled using Ipsos’s KnowledgePanel expect DeSantis and Ramaswamy to perform best, out of the seven-candidate field. According to a five-point scale that we calculated using respondents’ answers (with 1 being “terrible” and 5 being “excellent”), likely voters expected both DeSantis and Ramaswamy to perform “very good” (3.44 and 3.43 out of 5, respectively). They thought Haley would perform third-best (3.40 out of 5) and Scott fourth (3.20 out of 5). All of this is fairly in line with their pre-debate expectations in August.

When it comes to which candidates respondents are interested in, Haley saw the biggest bump since our poll before last month’s debate — 31 percent are now considering voting for Haley, up from 25 percent. Although she now has the third-most prospective support, she’s still got a long way to go compared to Trump (66 percent) and DeSantis (49 percent). About 1 in 4 likely Republican primary voters are also considering voting for Ramaswamy and Pence.

We’ll be watching to see how the candidates fare tonight, and if debate watchers’ opinions on who they’re considering voting for will change after tonight’s performances.

—Analysis by Holly Fuong of 538