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 candidates who are not on the debate stage tonight are still trying to make their case to voters, but face the challenge of being out of the almost-literal spotlight tonight. Some are also starting to be more candid about their prospects.

Former Arkansas Gov. Asa Hutchinson, who is pitching himself as a moderate conservative alternative to Trump, is in the difficult position of having been onstage at last month’s debate – and then not qualifying for tonight’s event.

Instead of trekking to California, Hutchinson spoke in Detroit this morning, not far from where Trump, who’s off the debate stage by choice, is holding a rally tonight. "I'm here, in Detroit, because I want to debate. Donald Trump is here in Detroit tonight because he wants to avoid a debate,” Hutchinson said at the presser.

Media attention is largely focused elsewhere today; only four cameras were at Hutchinson's event, according to ABC News campaign reporters Libby Cathey and Fritz Farrow.
Hutchinson wrote earlier this week that he is going to try to “increase my polling numbers to 4% in an early state before Thanksgiving,” setting a self-imposed benchmark for himself without directly saying whether he would withdraw or not if he doesn’t make it there.

He’s not the only one having a moment of campaign contemplation. Fellow offstage candidate and former Texas Rep. Will Hurd wrote today that he’ll continue campaigning, with a focus on New Hampshire, but that “our campaign is at an inflection point.” And last month, Miami Mayor Francis Suarez suspended his campaign about a week after the first debate aired. We’ll have to see if others follow in his footsteps after the dust settles from tonight, but it looks like Hutchinson and Hurd plan on staying in the game for now.

—Oren Oppenheim of ABC News