Donald Trump, Melania Trump

Two voters hold up a sign for Sen. Marco Rubio as presidential candidate Donald Trump, center, and his wife, Melania, visit a caucus site Monday at Saint Francis of Assisi Church in West Des Moines, Iowa.

(Jae C. Hong, The Associated Press)

CLEVELAND, Ohio - The joke was on us.

Donald Trump, the billionaire real estate mogul, has behaved like no other presidential candidate we've seen. He belittled Sen. John McCain, prisoner of war, for being captured. He mocked a reporter's disability. He called for a ban on Muslim immigrants.

Through it all, he was the closest thing Republicans had to a presidential front-runner.

The polls said so. Trump said so. Even some of Trump's rivals, who seemed resigned to a fight for second place in next week's New Hampshire primary, said so.

But at some point, something had to give, right? Tonight, in Iowa, it did.

There, after the first votes of 2016 were counted, Sen. Ted Cruz of Texas beat Trump. The caucuses established Trump as that which he hates: A loser.

But Cruz's victory and Trump's defeat by no means settle the volatile race for the GOP nomination, which officially will be awarded here in Cleveland this summer.

Some thoughts about what Iowa's results taught us.

1. Trump is a paper tiger.

Organizing Iowa is hard work. As a reality TV star and political curiosity, Trump was great at drawing thousands to hear him speak. But that doesn't drive turnout.

The caucuses have ratified the notion that Trump is beatable. And that notion soon could be reflected in New Hampshire. Polls there had shown Trump as a double-digit leader. Will they still love him tomorrow?

Trump, in a gracious concession speech, vowed to stay in the race.

2. Cruz has established himself as the top anti-establishment candidate.

It was a two-way race between him and Trump, and Cruz prevailed where it matters. More impressive about his Iowa win is that it came in spite of Cruz's opposition to the Renewable Fuel Standard - a lifeline for the state's ethanol industry.

3. Marco Rubio might have the most momentum.

The Florida senator was smart to keep expectations low. He exceeded them, appearing to finish a close third behind Trump and delivering a speech that you would be forgiven for mistaking as a declaration of victory. That could be enough to persuade more mainstream Republicans to rally around him as an establishment-friendly Cruz alternative.

But Rubio first has to prove himself again in New Hampshire.

4. Jeb Bush, Chris Christie and John Kasich made the right call.

All three spent caucus night in New Hampshire, giving them a head start on Rubio.

Really, there was nothing for the centrists to win in Iowa, which has a high concentration of evangelicals and social conservatives. The top three - Cruz, Trump and Rubio, in whatever order - seemed set. Even also-rans Ben Carson and Rand Paul were on better footing there. Of these three, Bush made the biggest play and performed the best.

Kasich, the Ohio governor, was poised to finish ahead of past caucus winners Mike Huckabee and Rick Santorum and, more significantly, Christie. Kasich spent little time in the state. Not that there are any bragging rights in seventh place, but Kasich will take it.

5. The next week in New Hampshire is going to be a brawl.

The airwaves there already are crowded with ads from the candidates and the so-called super political action committees that support them. And it's getting nasty, to the point where Kasich today admonished his friendly super PAC for attacking Rubio.

But now Rubio is an even bigger target. Not just for Bush, Christie and Kasich. For Cruz, too. Rubio has courted voters in both the establishment and anti-establishment camps. And he and Cruz have provided some of the best debate moments.

Desperation could set in for others. The Feb. 9 primary might be the last stand for Christie and for Kasich, though Kasich already has gamely announced a South Carolina swing beginning Feb. 10. It's hard to see both in the race after New Hampshire. Bush theoretically has the cash and organization to stick around a while.

Trump could stick around, too, in hopes of avenging his Iowa loss. He has plenty of his own money to spend. It could be his last stand, too. If so, look out.

6. It's time for the field to shrink.

Thanks for playing, Huckabee and Santorum. Lightning didn't strike twice for these past caucus winners. Huckabee suspended his campaign tonight. Don't expect Santorum, who began 2016 with only $42,000 in his campaign account, to stay much longer.

Carson is on borrowed time, too. Or at least he should be. He once was a front-runner in Iowa, but a lack of substance, combined with a poorly run campaign, doomed him. He finished in the upper tier in Iowa, but New Hampshire polls show no path for him there.

Worse for Carson, he was the subject of ridicule this evening as reports surfaced that he was headed home to Florida. His campaign pushed back on speculation that was about to drop out, with aides insisting the retired neurosurgeon only needed some fresh clothes.

That should do the trick.