She promised Iowans she wouldn’t formally endorse anyone and she says she’ll keep that promise even though there’s a ton of overlap between Rubio’s campaign and the team that helped Ernst get elected to the Senate in 2014. Rubio himself is the only Republican in the field who endorsed her during her primary in Iowa that year, and his PAC spent nearly a quarter of a million dollars to assist with her election effort. You’d think this would be the perfect time for a little quid pro quo. Watch the clip and you’ll see that it does sound a lot like an endorsement: She describes Rubio as “someone who is very near and dear to my heart” and segues into a speech about destroying ISIS, which is the bread-and-butter natsec message that he’s running on. The question mark here is whether what one of her spokesmen told WaPo is true: Supposedly, “she is willing to introduce any presidential candidate who asks her to do so if both can fit it into their schedules.” Does that mean she’s willing to turn up at a big “closing argument” rally for Trump next weekend if she has some free time, or is every minute of her schedule conveniently booked for the next week so that Rubio ends up as the only candidate who can use warm words from Ernst in his caucus pitch there?

Another question for you per the increasing likelihood that Trump’s going to win Iowa: Would that improve or damage Rubio’s chances of a good showing in New Hampshire? If, say, Trump pulls 36 percent next Monday compared to 26 percent for Cruz and 16 percent for Rubio, what do anti-Trumpers in New Hampshire do? At that point, having lost Iowa, Cruz could be seen as a bust; maybe some of his supporters start shifting to Rubio as the last best chance to deny Trump the nomination. In theory it’d be easier for Rubio to beat Trump head-to-head than to beat Cruz since he wouldn’t need to worry about attacks from the right against Trump except on immigration. Center-righties already like him and most conservatives would probably hold their noses for him despite the great Gang of Eight betrayal. On the other hand, if Cruz goes bust and Trump wins Iowa he might be unstoppable. What good will it do Rubio to have Cruz out of the way if Trump amasses a bunch of momentum and then cruises to a 40/25 win over Rubio in New Hampshire? I think, when push comes to shove, Rubio’s marginally better off with Cruz winning Iowa because that all but ensures a long race, even though it also increases the chance that Rubio finishes third in NH. I think he can still make his mark in South Carolina if he finishes a narrow third in New Hampshire, especially if the first two states were split between Cruz and Trump. It’s a rough outlook for anti-Trumpers, though, if we’re now gaming out who’s going to make the most effective last stand against Trump in South Carolina. Maybe it’s time to start gaming out the inevitable conservative third-party candidate instead.