Rubio’s biggest argument was his electability. He’s fresh, he’s young, he has an inspiring story, he’s Latino, he’s charismatic, he’s a great contrast to Hillary Clinton, he’s a great debater (usually!). Indeed, his debate fiasco was so bad precisely because it undermined one of the key arguments of his campaign. A guy who is liable to face-plant humiliatingly during a debate if pushed around a little too much is not a guy who is a guaranteed win against Hillary Clinton.

So now Rubio needs a new argument to justify his candidacy. Or rather, a new argument that proves the old one again. Rubio had great promise, and simply needed to show that he could win. Instead, he lost. So how can he show that he can win? By showing that he can take down Trump.

That’s how he can solidify the non-Trump, non-Cruz vote. That’s how he can show he can win political battles, instead of going into them with lots of potential and hype, and doing well but never quite sealing the deal. Rubio has avoided attacking other candidates to stay above the fray and preserve his image. That’s smart. But now the time for caution is over.

Everyone is attacking Trump the wrong way.