Marco Rubio’s campaign ended yesterday. He won’t acknowledge it and neither will his hardcore supporters for some days, but he is done. It was one thing when he was running more or less even with Cruz across the South, like he did on Super Tuesday, but Rubio has clearly lost his mojo, finishing behind Kasich in Maine and well behind Cruz in Kentucky and Louisiana. Rubio is running out of gas both metaphorically and physically. This is now a race between Cruz and Trump.

I say this as a guy who a couple weeks ago endorse Rubio as the best chance to beat Trump.

However, if I were Ted Cruz, I would be hoping that Marco Rubio does not drop out yet, at least not until after Thursday. Because the reason that Cruz was able to reach up and stun Donald Trump yesterday is that Rubio has picked apart Trump’s vanity and caused him to self-immolate in a way that no candidate has been able to either before or since. Rubio was able to expose Trump’s business record in a way that Cruz never was.

Moreover, Rubio’s insult comic routine exposed what an ugly, shallow, insincere man Trump is to an electorate that was almost ready to embrace him as inevitable.

Unfortunately, it also seems to have had the effect that it has destroyed Rubio’s chances at obtaining the nomination himself. Many voters who were horrified by Trump’s response were equally horrified by Rubio’s behavior that provoked it. In much the same way that Chris Christie exposed Rubio at a critical point in the campaign, only to see his own personal standing suffer as a result, Rubio has had the same thing happen to him with respect to Donald Trump.

Granted, I don’t think that Rubio had any sort of altruistic motive in doing what he did; I am quite sure he did it with the intent to win. But at the end of the day it had the salutary effect of allowing Cruz to present himself as the adult in the room and I think is quite a bit responsible for the fact that this is now a surprisingly tight race between Trump and Cruz.

If Cruz ends up winning this thing, he should send Marco Rubio a nice postcard or a thank you note or something. There’s probably been too much public bad blood between the two for any sort of unity ticket to ever occur, but I think if Cruz wins, we haven’t heard the last of Rubio.

For now, if you want to stop Trump, the clear remaining answer is Ted Cruz.