In that case, good news: Trump’s not really a Republican so attacking him should pose no problem. Also, hasn’t Rubio spent the better part of four months attacking Ted Cruz? Did I dream that, or is this part of some lame Cruz-attacked-me-first spin? Where is this “no attacks on Republicans!” rule coming from?

Opinion among conservatives seems universally to be that Rubio should throw everything he’s got at Trump. I’m of two minds about that. On the one hand, this is a real problem:

@allahpundit It makes him look like John Edwards in '04, running for veep. — Ross Douthat (@DouthatNYT) February 24, 2016

With every passing primary/caucus, Rubio looks more like Robin, less like Batman. — David Frum (@davidfrum) February 24, 2016

He looks like a beta male in a primary where a beta male is the worst thing you can be, far more so than being a fabulously rich big-government cronyist posing as a man of the people. My answer to that is this: What has scrapping with Trump done for anyone who’s dared to try it so far? Jeb Bush went after Trump for months, but only after Trump had so efficiently emasculated him that he ended up a nonfactor for the last six months of his campaign. Cruz has been dropping heavy ordnance on Trump for two months, prosecuting the case daily that Trump is a phony conservative and an enemy of the little guy (most recently in Nevada by noting that Trump wants to leave federally owned land in the government’s hands). Result: A favorable rating that’s nosedived and two straight third-place finishes behind Rubio, thanks in part to endless counterattacks from Trump on his eligibility, his likability, his honesty, and so forth. And Cruz is much, much better at attacking an opponent than Rubio is, I think. Rubio’s appeal to his fans (and beyond his fans, given his high favorable ratings) comes from the idea that he’s somehow above this type of nasty politics-as-usual, forever turning his eyes towards the shining city on the hill. Once he goes strongly negative on Trump, that’s at risk. Rubio also looks much younger than he is, which will feed perceptions that a war with Trump is really a match between a man and a boy. There’s no reason to think he’ll succeed in bombing Trump where Cruz failed.

Arguably, then, he’s better off staying sunny, being patient, and hoping that Cruz quits sooner rather than later to force the Trump vs. Not Trump race that represents Rubio’s only shot at winning. If Rubio goes to war with Trump now, his own numbers may fall and suddenly Cruz is back in contention to become the last “Not Trump” standing. If Rubio bides his time, on the other hand, Trump might surprise Cruz in Texas next Tuesday, effectively finishing him off and leaving Rubio as the only game in town for anti-Trumpers. Cruz fans understood the value of patience and detente with Trump very well for the last six months of 2015; now Rubio’s following the same strategy, minus the sick-making “Trump is terrific!” nonsense that Cruz laid on him, for another week. If and when Cruz is out, then Rubio will probably have no choice but to start attacking Trump as Trump will surely begin attacking him as his sole remaining real competitor. Understand, though: All we’re doing is gaming out long longshots here. If Rubio goes to war with Trump today, there’s maybe a 0.5 percent chance that he’ll hit Trump with something that’ll do real damage after everyone else in the race has tried and failed. If he continues to beg off, at least for a week, there’s maybe a one percent chance that Cruz will drop out and Rubio really will see the sort of 57/41 lead over Trump that that dumb, obvious outlier NBC poll gave him a few days ago.

But I’m open to persuasion. So go ahead and sketch out a scenario for me in which Rubio unloads on Trump, starting today rather than next week, and suddenly the race changes. We get a big round of “Trump’s not a conservative!” Super PAC ads, as though that fact’s not already priced into his stock, and then suddenly Trump’s on cable news every morning talking about Rubio’s eligibility being in doubt, his immigration record being dubious, and how America can’t send a boy to do a man’s job. Who wins that war of words? How does that get Rubio closer to 51 percent when Cruz is still in the race and will take encouragement from winning in Texas to continue his campaign even if he wins nowhere else next week?

Update: “Donald Trump is about to do terrible things to Marco Rubio,” wrote Paul Waldman yesterday about the coming Trump/Rubio war. Indeed he is. Why would Rubio want those terrible things to begin any sooner than they have to, especially with Cruz still kinda sorta viable?