Rubio and Cruz interrupted, insulted, and mocked the Republican front-runner. Rubio obviously had the moment of the night, in the space of a couple of minutes exposing Trump’s utter vacuity on health-care policy, catching him repeating himself when Trump said he doesn’t repeat himself, and mocking Trump’s signature lines. Cruz was more prosecutorial and not as memorable but effective nonetheless. If I had any criticism, it was that they weren’t relentless enough and occasionally let up on the attack (this Peter Spiliakos post from a while ago nailed it). At one point, all three of the candidates were talking at once — this is what Trump has done, force everyone down to his level of reptilian politics where all that matters is trying to talk over people to establish your dominance…

It is true that the core of Trump’s supporters will stay with him, but there is a lot of room between 24 percent (Iowa) and 46 percent (Nevada). There is such a thing as a marginal Trump supporter, and he or she is susceptible to persuasion. At the very least, tonight opened up avenues for further attack on and examination of Trump’s tax returns, his hiring of foreign workers, etc. If there were a coordinated anti-Trump effort, ads on some of these themes would follow in short order and surrogates would be out hammering away at them. But it’s a step in the right direction that other candidates are fighting by the only rules that will make it possible to take him down a notch — namely, the rules the mogul himself has used to establish his current dominance in the GOP race.