Christie criticized the idea that the president could cozy up to Vladimir Putin, noting that all recent presidents have failed to engage Putin by not being tough enough. He then hit Trump for having said that Putin was "brilliant and a great leader." As the night has worn on, Christie continues to be really the only candidate who is bothering to attack the guy who is 40 or more points ahead of every other candidate in national GOP primary polls.

— Analysis by Geoffrey Skelley of 538

Ilia Calderón is asking about sending U.S. troops to Mexico. In a late August/early September survey by Morning Consult, 41 percent of Republicans said they thought that sending U.S. troops to fight cartels in Mexico would be “very effective” at limiting the supply of illegal drugs in the United States. Other strategies had more support among Republicans, such as sending more resources to the U.S.-Mexico border (54 percent), empowering U.S. law enforcement to combat opioids (45 percent), and punishing drug violators in the United States (43 percent).
—Analysis by 538

Haley going after Ramaswamy was a recurring theme in the first debate. They were the standout candidates in our polling last time and there was a lot of speculation about Ramaswamy moving up in the polls — perhaps even surpassing DeSantis. But since August, Ramaswamy has actually lost support, to the point where Haley passed him in our polling average today. It makes sense that they're trading blows again; this seems to be a successful strategy for Haley, and Ramaswamy can't help but take the bait.
-Analysis by G. Elliott Morris of 538

The candidates are discussing support for Ukraine. About half (49 percent) of Republicans and Republican-leaning independents say that vital U.S. interests are not really at stake in the war in Ukraine, according to an August Echelon Insights survey. Thirty-seven percent disagree, saying that if Russia wins, vital U.S. interests and values are threatened. Fourteen percent are unsure.
—Analysis by 538

I’m monitoring Pence tonight, and I’ve got to be honest: I don’t know how much he can do to increase his standing in the primary other than hope that other candidates implode. During the last debate, he had plenty of speaking time and, given Trump’s hatred for his former vice president, a pretty strong reception from the Fox News crowd. But still, nothing substantially changed. Voters expected him to give an average performance, and he pretty much delivered. He’s averaging less than 5 percent in national primary polling.

It’s not clear where Pence has room to grow. He’s better known than any candidate on tonight’s debate stage, and voters seem to have decided how they feel about him. If he’s a second-choice to similar candidates — others who, say, share his dislike of Trump but would nonetheless support him in a general election — Pence could benefit from a smaller field. So, the best thing Pence could do might just be to stay the course, continuing to get enough support to appear on a debate stage and waiting out lesser-known and underfunded candidates.

—Analysis by Leah Askarinam