The funniest part of this is that Rubio thinks the GOP will still exist in 2020. By then I assume the right will have split into a conservative party, a white-identity party, and a Democrat-lite party to accommodate all of the Beltway Republicans who won’t have a political home otherwise. Does Marco run for the nomination of the first one or the third?

No, just kidding. The real impediment to a Rubio run in 2020 will be that President Trump will be running unopposed for his second term. Right, Trump fans?

Let’s approach this logically. If Rubio had endorsed Cruz the day after he lost Florida and dropped out on March 15th, how would the race be different now? Which states that went for Trump would have flipped to Cruz? The only Trump victory between Florida and his inevitable dominance in New York and the mid-Atlantic this month was Arizona on March 22nd, where he won by more than 20 points and where Rubio’s brand of immigration moderation wouldn’t have played well. To believe Rubio’s endorsement would have mattered to any of these races, you need to believe that Kasich’s supporters are all really just Rubio supporters who were waiting for their favorite candidate to say the magic words to get them to finally, grudgingly vote for Cruz. Does anyone buy that?

Marco Rubio won’t be endorsing Ted Cruz during the Republican presidential primary, but he’s likely to back the Texas senator at a contested convention — if it gets that far…

Rubio has already helped Cruz by renting him his fundraising list, calling him “the only conservative left in the race,” withdrawing his name from the primary ballot in select states so as not to siphon votes from Cruz and petitioning to hang on to some of the 171 delegates he won to keep them from going to Donald Trump…

“Marco wants Donald to lose. If he thought his endorsement would help in California or in Indiana, which it won’t, then he would probably do it,” the source said. “But what Marco isn’t going to do is just endorse Ted, watch Trump win anyway and then, in four years, watch Cruz use Marco’s endorsement against him if they both run for president again,” [a Rubio insider] said…

“Trust me, for us, the best scenario is for Ted Cruz to be the nominee this year,” another top supporter said. “It would knock Trump out. Then Cruz would run against Hillary and get slaughtered and he won’t be our problem in four years if Marco runs again. And I think he’ll run again.”

How, and why, would Rubio run again in 2020 unless he’s elected governor in 2018 first? He’ll have been out of office for four years, having failed dismally against Trump in his home state primary in 2016, and he’ll be facing a new crop of Republican (or conservative) up-and-comers — Nikki Haley, Ben Sasse, Tom Cotton for starters. Cruz will probably be back too. That’s stiff competition for a candidate who underwhelmed this year. Meanwhile, the pre-campaign media narrative in 2020 will be “Will there be another Trump this time?” and they’ll work hard to make sure that there is, if not Trump himself than some other celebrity populist. And the prize for the winner of the primary, having somehow navigated all that, will be facing an incumbent Democratic president in the general. I don’t know why Rubio would want to bother with any of it. He’s better off quitting politics for the next four years, making some bank, then plotting his comeback in the next decade.

And there’s a bigger problem: A Rubio comeback in 2020 assumes that the right will react to a Trump loss this year by becoming less, not more, radical. The party’s base grew more conservative after McCain’s loss, then more conservative after Romney’s, but now, watching Trump fail after running on mass deportation and barring Muslims from the country, they’re supposedly going to throw in the towel and accept a more mainstream nominee next time purely in the interest of breaking the Democrats’ stranglehold on the White House. I don’t buy that. If it’s true, as the left often insists, that Trumpism is driven by a white backlash to the country becoming more minority, there’s no reason to think that trend will reverse. It may be that some soft Trump supporters conclude nationalism is an electoral dead-end if he loses badly enough this year, but national demographics will go on being what they are. The Trump contingent next time might be smaller but more committed, and even a smaller group is likely to be large enough to deny a Republican nominee like Rubio the right-wing unity he needs to contend seriously in the general election. And of course, there will be “soft conservatives” who may draw the opposite lesson from a Trump defeat this fall, especially if it’s closer than everyone expects — namely, that there are more nationalists and reactionaries in the party than conservatives (which seems awfully plausible to me) and the only chance there is for right-wing unity against Democrats in a general election is conservatives reluctantly swinging behind nationalists, not vice versa. Rubio should be thinking more about that than about some lame ad Cruz might run against him in 2020 reminding everyone that Rubio endorsed him over Trump. Is he prepared to become a nationalist, or more of a nationalist, to make himself politically viable for national office?

Oh, by the way: The latest poll of Florida has Hillary leading Trump by … 13 points, thanks in part to Trump’s sterling 10/87 favorable rating among Florida’s Latinos. Cruz trails her badly too (although not quite as badly), but Cruz is likely to be an ex-candidate for all intents and purposes 36 hours from now. Good luck in 2020, guys.