At a loss to explain Trump veering from frenemy to enemy to friend of Cruz again at the debate in the span of about five days, Joe Scarborough wondered this morning whether some “inside deal” has now been struck between the two. I doubt it. What would that deal look like? Cruz needs something from Trump, namely, a truce that’ll keep Cruz viable for Trump voters, but Trump doesn’t need anything from Cruz. What could Cruz offer him to get him to back off? (Trump’s not going to be anyone’s VP. C’mon.) Even if the deal is “we can make this a two-man race if we avoid attacking each other,” how does that benefit Trump? Trump needs either a three-man race, to keep the conservative and center-right majority divided, or a two-man race against someone unpopular like Jeb Bush. If he goes head to head with Cruz, he loses. Probably badly.

I sympathize with Scarborough’s confusion, though. I wrote a whole post on Friday about why it doesn’t make sense for Trump to hold his fire against Cruz. What does he gain from it at a moment when one respected poll has him down 10 to Cruz in Iowa? It’s one thing to hold fire when you’re ahead, it’s another to do it when you need to make up ground. Trump’s track record of damaging other candidates with attacks thus far this year has ranged from spectacularly successful (Jeb) to no real harm done to either side (Rubio), so there’s no obvious cost to attacking either. How does he benefit from shelving the talk of Cruz being a “maniac” who can’t work with anyone in favor of blather about Cruz having a “wonderful temperament”? The display in the clip below was practically an endorsement for Trump fans to consider backing Cruz as their plan B if it comes to that.

One possibility is that this is just Trump being Trump at a debate. He’ll scrap with other candidates face to face if sharply provoked, as Bush did last night, but usually he’s weirdly and uncharacteristically fraternal during and after these events. And not just exclusively to Cruz’s benefit; last night he called Ben Carson one of the finest men he’s known after spending a month on the trail wondering if Carson needs psychological help for his violent outbursts as a kid. Maybe Trump just dislikes attacking people to their face? Or maybe he sees these debates mainly as a way to reach people who aren’t paying attention to the race day to day and wants to put on a more “presidential” demeanor for them. Either way, there’s an easy tell: If Trump starts attacking Cruz again in interviews and at rallies then obviously the detente yesterday was a one-night-only thing for the debate. We’ll know soon.

Another possibility: Maybe Rush Limbaugh and Mark Levin attacking Trump for calling Cruz a “maniac” backed him off. Trump’s coalition is famously all over the map ideologically, but there are some grassroots conservatives in the mix. If he picks a fight with Cruz and conservative icons side with Cruz against him, maybe that’s enough to shake loose some of Trump’s right-wing fans. Result: He slips further in Iowa while Cruz, the likely beneficiary of those newly undecided votes, climbs higher. In other words, this is a strategic retreat. In that case, though, when does he start advancing again? Unless he thinks Cruz is going to fade of his own accord, which literally no one else does, he’s going to have to hit Cruz at some point, which will trigger more wrath from talk radio, more questions among right-wing Trump supporters, and so on. He can’t avoid this confrontation indefinitely. He can avoid it for now, but like I say, what good does that do him? He’s better off attacking Cruz ASAP in order to give those attacks the most time possible before Iowa to resonate with voters.

Here’s what I think is happening. Trump, who’s always fanatically watching his polls, has noticed that he’s pulling his best numbers yet lately in national surveys. He cracked 40 percent a few days ago in Monmouth and nearly matched that in WaPo. As for that pesky Selzer poll showing Cruz way ahead in Iowa, I bet he’s now convinced himself that that’s an outlier and that the national polls are the true indicator of the state of the race. As such, it’s not a matter of Cruz “fading on his own,” it’s a matter of Cruz being headed for defeat in Iowa whether he realizes or not. And if Trump is destined to win this race via walkover, what’s the point of making enemies on the right by attacking Cruz now? Better to gladhand him, rebuild the goodwill he has among (some) conservatives, and hope that that’s enough to get righties to support him when he inevitably tops Cruz in Iowa and sweeps to the nomination. In other words, maybe Trump is using a variation of Cruz’s own strategy towards him: He knows there are Republican voters out there who prefer someone else, but he thinks he can bring those voters around — if not in the primary then in the general election, when he’ll need them. That’s the best I can do to explain him laying off Cruz here, especially on immigration. Trump could hit Cruz from the right on amnesty at any moment by pointing out that he won’t commit to deporting all illegals. Not only would that make some of Cruz’s right-wing border-hawk fans think twice, it’d be thorny for talk radio stars to defend Cruz on it. And yet Trump refrains. How come?