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

Trump maintains a lead of 27 percentage points over Haley, his nearest competitor in South Carolina, according to polls conducted since the first debate. Haley’s average support has grown by 9 points since the first debate, while DeSantis and Scott have fallen.

According to a September survey from Beacon Research/Shaw & Co. Research/Fox Business, 69 percent of likely South Carolina Republican primary voters say they support their first-choice candidate strongly, while 28 percent say they support them only somewhat. Among those that list Trump as their first choice, 86 percent say they support him strongly, while the second-place candidate, Haley, has only 57 percent saying the same.

In a September survey by Monmouth University/The Washington Post, South Carolina primary voters are split on whether the Republican Party should nominate a candidate who agrees with them on major issues (51 percent) or one who can beat Biden (45 percent). Among voters who say they are very or somewhat conservative, selecting a candidate who can beat Joe Biden is more important by a margin of 7 and 11 percentage points, respectively. Voters who say they are moderate or liberal prefer a candidate who agrees with them on major issues by 31 percentage points.

—Analysis by 538