Marco Rubio's strategy, long criticized by the professional political punditry, started looking awfully good after his strong third-place finish in Iowa. He seemed on the verge of breaking out. Until Rubio showed up in New Hampshire and totally face-planted.

The young Florida senator ran a mild, low-key, non-adversarial campaign. Like a made-for-TV movie's idea of a presidential campaign, with ads almost designed to be bland. (Compare that to Ted Cruz's aggressive, clever, and downright funny ads.) Rubio was derided by some critics for staying low-key. He was derided for not having enough of a ground game. He was derided for not spending enough time sucking up to prominent activists and machers. He was derided for focusing on no state in particular.

But then, in Iowa, all of Rubio's bets paid off. By staying low-key, he didn't peak too soon, like so many who had their 15 minutes too early in the 2012 cycle, or 2016 flameouts like Scott Walker and Ben Carson. Instead, Rubio peaked right as Iowa rolled along, outperforming expectations and gaining momentum going into New Hampshire. If Rubio hadn't face-planted during the debate, I think he would have finished second in the Granite State. Most of the non-Cruz, non-Trump candidates would have left the race, and Rubio would have looked like the inevitable recipient of the non-Cruz, non-Trump vote (and the establishment support and money that goes with that).

Instead, Rubio finished a massively disappointing fifth. He no longer looks like the Next Great Hope of the GOP, the establishment candidate who can win. Right now, Marco Rubio is just a guy who finished third in Iowa and fifth in New Hampshire.

So, what's next?

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. Candidates and pundits alike are attacking him either for being a jerk — that's part of his appeal — or not being a conservative, which is also part of his appeal. The New York Times' Ross Douthat put it perfectly:

To attack him effectively, you have to go after the things that people like about him. You have to flip his brand.

So don't tell people that he doesn't know the difference between Kurds and the Quds Force. (They don't either!) Tell people that he isn't the incredible self-made genius that he plays on TV. Tell them about all the money he inherited from his daddy. Tell them about the bailouts that saved him from ruin. Tell them about all his cratered companies. Then find people who suffered from those fiascos — workers laid off following his bankruptcies, homeowners who bought through Trump Mortgage, people who ponied up for sham degrees from Trump University. [The New York Times]

Jeb plays the pearl-clutching victim with Trump, scorning him for calling John McCain bad names, and playing up his conflict with Trump in the media while his super PACs spend no money attacking Trump and lots of money on his petty vendetta against Rubio. Sad!

Rubio should go a different route. He must mount own his attack against Trump, and do it himself, instead of having someone else cut an ad. He should publicly and quite clearly challenge Trump to a fight, and win that fight.

That's how he becomes the non-Trump, non-Cruz candidate — the candidate of the majority of voters and stakeholders of the Republican Party, and hence that party's nominee for president of the United States. He can do it. But time is running short.