Marco Rubio leaves New Hampshire having learned a hard truth: Live by the expectations game, die by the expectations game.

Rubio was never expected to win New Hampshire, just like he was never expected to win Iowa. It's typically very hard to win the nomination without either. But his campaign had made its plan very clear: the 3-2-1 strategy.

Rubio made the 3 part in Iowa, finishing third there. But he failed to get the second-place finish in New Hampshire his campaign was setting up for. Instead, Rubio goes to South Carolina with a 3-4 or maybe even a 3-5 record.

The 3-2-1 strategy, explained

Here's how the Rubio campaign envisioned things going.

Rubio would finish third in Iowa — and would do well enough to surprise many of the pundits who'd dismissed him as an also-ran behind Donald Trump and Ted Cruz. This would win him support among New Hampshire Republicans, who are both more moderate than Iowans (bad news for Cruz) and famously late to decide, which would be good news for someone getting good press coming out of the Iowa caucuses.

Then, having placed second in New Hampshire, he'd go to South Carolina with more momentum still — and manage to win the state outright from under Donald Trump's nose. From there, it would be a simple matter of cleaning up the pieces: The party establishment would finally have united behind him, and he could outlast Trump and Cruz by outspending them.

Here was how things went.

Rubio did, in fact, finish third in Iowa. In fact, he did much better in Iowa than many were expecting: He won 23 percent of the vote and was only a percentage point or two behind second-place Donald Trump.

Because he did even better than his campaign was predicting, he managed to "win" Iowa's expectations game, even without winning the actual caucuses. That gave him the momentum his campaign was promising. He rose in the polls going into New Hampshire.

But the thing about beating expectations is the next time around, the expectations get higher. And the 3-2-1 strategy set up Rubio's campaign for this. They had turned a third-place finish into a win in Iowa, but anything less than second would be seen as a loss in New Hampshire.

And after Iowa, once he started surging in the polls, it started to look possible that Rubio could actually beat Trump outright — raising expectations even more.

NH prediction, 5 days out: Rubio 25, Cruz 22, Trump 19, Kasich 17, others single digits. #NoGutsNoGlory — Bill Kristol (@BillKristol) February 4, 2016

Then something happened.

Something definitely arrested Rubio's momentum. How's he going to get it back?

Did Rubio's disastrous debate performance — "the glitch" — doom his campaign for good? He thinks it was — or at least, he thinks it doomed him in New Hampshire.

Rubio: "Our disappointment is not on you, it's on me. I did not do well on Saturday night. But listen to me: That will never happen again." — McKay Coppins (@mckaycoppins) February 10, 2016

Whether or not he's right, something definitely arrested Rubio's post-Iowa momentum in New Hampshire.

And the moment Rubio started tumbling in the polls just happened to be the moment a lot of New Hampshire Republicans finally made up their minds. 46 percent of primary voters told exit pollsters they'd decided in the "last few days" who they'd vote for.

Twenty-two percent of those voters went for Donald Trump, but 21 percent went for John Kasich — giving Kasich the benefit of the late-breaking establishment vote that Rubio so desperately needed. If even half those voters had gone for Rubio instead, he would have easily gotten the second-place finish.

Instead, with nearly three-quarters of precincts reporting, Rubio was winning barely 10 percent of the vote. That's a lot worse than he did in Iowa, where he won 23 percent of the vote.

That's not to say that Rubio can't reverse his fortunes yet again. But he's starting from scratch. This goes against the premise of the 3-2-1 strategy: that finishing strong in Iowa would give Rubio the momentum to pull ahead of everyone but Trump in New Hampshire, and then give him the momentum to pull ahead of Trump himself in South Carolina.

But here's the problem for Rubio: Trump's lead in South Carolina has been commanding. It wouldn't have been easy to topple him even under the best of circumstances. It's certainly not going to be easy for a man who appears to have taken the momentum he had and squandered it, all in the course of a week.