If they’re serious about this, it’s next to impossible to see how Rubio beats Trump there. And if Rubio doesn’t beat Trump there, it’s next to impossible to see how he’s the nominee, even at a brokered convention.

“For the candidates who have not yet won a state, who have not racked up significant delegates, I ask you to prayerfully consider uniting,” Cruz said. Going forward, Cruz’s team plans to make a play for Florida, Rubio’s must-win state, hoping to benefit from a cage match there between Trump and Rubio. “We will actively campaign in Florida,” said a senior Cruz aide. “A food fight between those two in Florida, that’s a good opportunity. We’re gonna make a strong play in Florida.”

The last poll taken of Florida had Trump at 44 percent, Rubio at 28, Cruz at 12, and Kasich at 7. Cruz and Kasich aren’t going anywhere before March 15th, so for Rubio to pull the upset two things need to be true. One: The polls are overestimating Trump’s lead — which is possible, given that they grossly overestimated it in Virginia. Two: Florida voters come to see the race as a binary choice between Trump and Rubio. That’s also possible given the inevitable media hype about “Rubio’s last stand” and a win in Florida acting as rocket fuel for a Trump nomination, but the more aggressively Cruz and Kasich contend the state, the harder it’ll be for that binary choice to develop. Frankly, Cruz fans in Florida have a very good reason to stand by their man instead of switching to Rubio. If Rubio loses the state, he’s all but done and may well drop out and endorse Cruz the next day. A “strong play” in Florida by Cruz, in other words, is an attempt to kill Rubio outright even though Rubio’s the only conservative there who stands an outside chance of winning the state. Cruz is going to try to narrow the race to him and Trump even if it means ceding Florida to Trump. That’s the most dangerous strategic gambit yet in a race that’s been full of them.

Is it unfair, though? Cruz finished with 43.8 percent of the vote in his own home state of Texas last night, a nice win (and a stronger finish than the polls had predicted) but still well short of the 50 percent threshold he needed to turn Texas into a winner-take-all state. That would have netted him 155 delegates, putting him right in the thick of it with Trump for the overall delegate lead. It also would have meant a strong boost in the “Cruz is for real” media narrative today. But he fell short. Why? Because Marco Rubio insisted on contesting Texas too. His allies spent big money there. And what Rubio got for his trouble was — ta da — zero delegates, because he failed to meet the 20 percent threshold in Texas needed to qualify. He ended up a little shy of 18. If Rubio had bailed out of the state altogether, there’s a chance that a chunk of his conservative support would have gone to Cruz, giving him the 50 percent mark he needed. As it is, the only candidate who benefited from Rubio’s campaign in Texas was Donald Trump, whose overall delegate lead was protected by the fact that Cruz couldn’t turn Texas into winner-take-all. Why shouldn’t Cruz repay the kindness by going hard after a strong showing in Florida, even at the price of destroying Rubio’s candidacy? If Rubio doesn’t give a rip about conservative unity in the name of defeating Trump, why should Cruz?

But that’s too simple. There’s a big difference between Rubio’s position in Texas and Cruz’s position in Florida. Namely, Texas is a proportional state whereas Florida is winner-take-all. Rubio had a good reason to compete in Texas even though he knew very well that he’d finish a distant third: If he had cracked 20 percent, he would have netted some delegates. Third place in Florida gets Cruz nothing except the satisfaction of having sunk the one guy in the race who’s probably best equipped to hold Trump’s margins down in the blue and purple states to come. (On the other hand, many of the states to come are closed, rather than open, primaries and Cruz has fared well in those.) And don’t forget, even if Cruz succeeds and Rubio ends up dropping out and endorsing him, not all of Rubio’s voters will go along. Some segment of them towards the center will back Trump. In fact, there were various reporters on Twitter tweeting yesterday that they’d met voters who were trying to decide last-minute between Rubio and Trump, which seems like a strange choice to the sort of ideologues who write and read political blogs but is less strange to casual voters, who vote for who they “like.” It’s almost a given that if Trump knocks out Kasich on March 15th, Cruz is probably the last guy of the big three that Kasich would endorse — which means still more centrist votes for Trump.

All of this is a long way of saying that Cruz needs to decide, in as clear-eyed a way as possible, if he truly believes he can beat Trump head-to-head on the inhospitable electoral terrain to come. Is he the right’s best chance of stopping Trump in the general, or is the best option now to have everyone stay in the race and keep running in hopes of collectively denying Trump a majority of delegates? If Cruz honestly thinks he can beat Trump one-on-one, he might as well go for broke and try to take out Rubio. If he doesn’t — and even as a Cruz fan, I don’t think he can — then contesting Florida is a catastrophe, a death blow to the #NeverTrump contingent (at least in the primary). Does anyone see Cruz beating Trump in the northeast, for example, even with Rubio behind him? I’d go so far as to say that if Cruz is aggressively contesting Florida a week from now, a potential third-party candidate in the general election like Mitt Romney might as well start moving aggressively to get on the ballot. The primary will effectively be over on March 15th if Trump pulls it off in Florida and Ohio, whatever Team Marco may say about running all the way to Cleveland.

One other point. I wonder if Rubio’s insult-comic attacks on Trump over the past week haven’t inadvertently made Cruz more viable as a potential consensus choice for a fractured GOP. That seemed implausible 10 days ago: Cruz and Trump had been killing each other for the past two months, with Rubio ducking confrontation. But now that Trump and Rubio have gotten personal with each other, Cruz’s refusal to respond with the same kind of “Trump’s spray tan is weird!” digs may make him comparatively acceptable to Trump fans. It’s one thing to attack Trump for not being a conservative, it’s another to call him a con artist whose fingers are tellingly small. That may prove useful to Cruz if we end up deadlocked at a brokered convention.