Republican presidential candidate, Sen. Marco Rubio, R-Fla., left, answers a question, as Republican presidential candidate, businessman Donald Trump listens, during the Republican presidential debate sponsored by CNN, Salem Media Group and the Washington Times at the University of Miami, Thursday, March 10, 2016, in Coral Gables, Fla. (AP Photo/Wilfredo Lee)

In what was basically the Republicans’ closing argument against the bizarre notion that Donald Trump might actually win the party’s nomination, Trump’s competitors decided, for the most part, not to argue at all.

In what may have been the final GOP debate, in what should have been a night of folks-you-can’t-be-serious desperation, the candidates decided to try civility instead, making nice with The Donald as he made nice with them.

Trump didn’t call Rubio “Little Marco” or Cruz “Lyin’ Ted,” and, in return, they, along with John Kasich, didn’t say Trump was a con man who would destroy the party and possibly the country. Conceptually it was a disaster, and in just about every other way, too.

If the purpose of the debate — as it had to be — was to show that Trump was an ill-informed demagogue who is playing to people’s worst instincts, it was a spectacular failure. I can’t say what was the worst moment of the night because there were so many. But it may have been, late in the debate, when CNN moderator Jake Tapper finally got around to asking Trump about the white guy who sucker-punched a black protester as he was being peacefully escorted from a Trump rally.

Trump said he didn’t like it, but explained that his supporters are incredibly angry at what’s happening in America.  “There is some anger,” he said. “There’s also great love for the country. It’s a beautiful thing in many respects. But I certainly do not condone that at all.”

Of course, as Tapper then noted, Trump has infamously egged on his supporters at various rallies, saying once that he wished he could punch a protester. Called on it, Trump replied that, hey, some of the protesters are “bad dudes.”

There was nothing unexpected in Trump’s response. (He later called the Tiananmen Square protests a “riot.”) What was, well, sad, though, was that the other guys let him get away with it. They each had a chance to weigh in and none of them hit Trump for the ugliness he encourages in his supporters or the report that his campaign manager had grabbed a Breitbart reporter with sufficient force to leave bruises. Cruz came the closest when he mocked the one-hand pledge taken at a Trump rally, but Trump said it was all a joke and Cruz, for once, backed down.

What was going on?

You saw the previous debate, right? And the one before that? The chaos. The nastiness. The Rubio penis joke.

In the most recent Super Tuesday, Rubio, the great establishment hope, got zero delegates and rarely broke out of single digits. He had to apologize for trying to out-Trump Trump – he said he had embarrassed his kids — and instead went back to being Rubio the serious policy candidate, the one who parrots his stump speech at every debate. Of course, that version of Rubio wasn’t doing much better in the voting, but at least he was getting a few votes.

Cruz, meanwhile, has set himself up as Trump’s main competition, and all he wants to do is keep it that way. There was no advantage to Cruz playing the bad guy, even if that’s his default position. If it does come down to Trump and Cruz, Cruz is counting on the fact that even if no one in the party likes him, he’s not quite as scary as Trump. And Cruz, who was in fine debating form, did say that if Trump were the nominee, Hillary Clinton would be president.

Kasich’s play is, of course, to be above the fray, and that’s pretty much where he stayed. And so about a half hour into the debate, Trump, a model of restraint by Trumpian standards, commented on how surprisingly civil the night was — and that was that.

It wasn’t as if there weren’t policy clashes. Trump showed how little respect he has for the process by coming to Miami without preparing anything to say about Cuba. Rubio, the son of Cuban immigrants, embarrassed him on the topic, or would have if Trump could be embarrassed or, for that matter, if Rubio weren’t so reflexively opposed to relations with Cuba. Cruz, after listening to Trump stick to his anti-Islam rhetoric and trade-war threats, explained that the world was a little more complex than saying “China bad, Muslim bad.”

You’d think in a serious policy debate that Trump would be the sure loser. He was called out for saying he could fix Social Security by attacking waste and fraud. And that Common Core had been imposed on the states. And so it went for most of the night, and yet Trump was clearly the winner.

There are still months to go in the primary season, but next Tuesday is being called Super-Duper Tuesday, with voting in winner-take-all Florida (where Rubio has to win), in winner-take-all Ohio (where Kasich has to win), in Illinois, in Missouri, in North Carolina. Trump could well sweep. Cruz needs some kind of split decision. If the math holds, all Rubio and Kasich can do is try to stay alive by winning in their home states and hoping something happens.

Trump, meanwhile, ended the night by calling for the party to unify around him. And why not? It was the same night he had announced that Ben Carson was about to endorse him — the same Ben Carson he had once called a psychopath. On Twitter, they were saying that, with the endorsement, Carson had just proved Trump’s point. And at that point, I don’t know what else there is to say.

Mike Littwin writes for The Colorado Independent (www.coloradoindependent.com).