Quote of the Day:

I have no idea how this debate will affect the polls. We are heading into the dark side of the moon for politics, as voters cut themselves off from the news to enjoy the Christmas break. So it may be that the biggest effect is a delayed one as people discuss all this around the holiday dinner table.

–Jonah Goldberg

Calling last night's debate the "among the most substantive we've seen in a long time," Goldberg agrees with most commentators this morning that the Ted Cruz-Marco Rubio debate within the debate was the most notable feature.

Donald Trump couldn't answer a lot of the questions, but it probably won't hurt him. He did vow to remain in the Republican party, for what that is worth. Dr. Carson is a good man who was out of his depth politically. As "George Bush" said in a return to SNL last week, running the country "isn't brain surgery."

Jonah on Trump last night:

He had two very strong answers. His lament about the wasted money and lives in the Iraq war undoubtedly struck a chord with many – and it was entirely coherent. And his vow to stay in the GOP was about as close as Donald Trump gets to statesmanship.

And some of his answers were mortifyingly awful. His decision to whine about the unfairness of the undercard-debate questions rather than answer the question asked was pathetic. His answer on the nuclear triad was an embarrassment. Yes, yes, lots of people don’t know what the nuclear triad is. But most people aren’t running for president. Moreover, he clearly couldn’t even bother to listen to Hugh Hewitt’s hints about what it was.

Also, don't forget that Hewitt asked him about the nuclear triad at great length in August, and he couldn’t answer it then, either. Call me crazy, but someone running for president should know enough about the nuclear triad to at least a fake a plausible response. His refusal to recant or explain his vow to kill the families of terrorists was shameful (and please don’t tell me what he meant to say. He couldn’t explain it. At all.).

Jeb Bush belatedly has improved game and his saying, "Donald, you are a chaos candidate" was arresting–except that it probably alienated Trump's loyal supporters and made Bush look even more like a candidate of the establishment, whatever that is. Not to make too much of the SNL skit, but it's odd that George W. Bush turned out to be the best politician in the family.

Rubio and Cruz skirmished on NSA surveillance and how interventionist our foreign policy should be. This isn't, going to be as conclusive, National Review's Ramesh Ponnuru observes, as another issue on which they have taken different positions:

My starting point includes the hunch that most Republican voters don’t have strong views on NSA surveillance: They have, instead, competing impulses, which lead them to worry both about national security and privacy. Nothing either senator said is going to strike most of them as obviously wrong or unreasonable, but they might mildly prefer Cruz for giving each impulse its due. I think something similar is true of foreign policy: Most voters aren’t going to make a judgment about what the right course in Libya was, let alone cast their ballot on that basis.

Immigration is different. A lot of voters do care about it, and Rubio is on the defensive. He may be able to carry the argument that Cruz has favored giving legal status to illegal immigrants in the past–something Cruz strongly disputes–and that he is open to it even today, and that the difference between their positions is therefore small. But Cruz can always retort that on the bottom-line question, were you for or against the amnesty bill backed by Dick Durbin and Chuck Schumer and Barack Obama, they were on opposite sides. I don’t think that position will doom Rubio, but it will hurt him with Republican voters.

Commentary's Jonathan Tobin also found the Crubio exchange important:

The point is that their tussle isn’t just a personal fight between two ambitious young men but one over the future direction of the Republican Party.

But, Tobin notes, the future of a Republican party in which Donald Trump leads his nearest competitor by double digits in not at all clear and Tobin pessimistically argues, when it comes to the current frontrunner,  it "isn’t likely that an objective analysis of his positions on war and peace issues actually matters."