ANALYSIS: Donald Trump Tames His Ultimate Enemy -- Himself

— -- At what might be the final presidential primary debate of a rambunctious cycle, the front-runner decided to focus on the presidential part.

The tamest debate by far on the Republican side gave Donald Trump a chance to show he can be on his best behavior. It also came at an inconvenient time for a Republican Party filled with voices who believe the party is in danger of a meltdown.

Trump didn’t moderate his stances – he stood by his claim that “Islam hates America,” and took on Sen. Ted Cruz when it looked like the debate might turn to a one-on-one – and he surely didn’t overwhelm the crowd with substantive policy. But not once did Trump reference “Little Marco” or “Lying Ted,” to say nothing of his hand size.

Even as Trump stumbled through policy questions with a typical lack of details, his rivals passed on most opportunities to pounce. Trump was left marveling at the civility on stage, just days before voting in a swath of critical states could effectively seal the nomination for him.

“We're all in this together,” Trump said. “We're going to come up with solutions. We're going to find the answers to things. And so far I cannot believe how civil it's been up here.”

Confronted with the scattered violence that’s erupted at his campaign events, Trump said he didn’t think he bears responsibility – “I hope not,” he said – even when confronted with words demonstrating how he’s contributed to raucous scenes. His rivals didn’t really lay it as his feet, though, either.

Trump at one point bragged about using foreign workers to fill jobs, saying he “shouldn’t be allowed to use” the federal program that allows it. But his rivals didn’t hit him for it.

It might prove an inconvenient time for the Republican Party to discover civility in such forums, given the urgency so many see in stopping Trump. Yet they also may be getting used to the idea of Trump as their nominee, so perhaps it’s just as well.

It was as if, with all other manner of attacking Trump having fallen short, Ted Cruz, Marco Rubio and John Kasich decided on a new approach: don’t try at all. Each is pursuing his own, mainly regional strategy, some predicated on a slog toward a contested convention, and attacks on Trump just don’t fit with that at this moment.

Cruz tried to draw out Trump as a creature of the establishment, in a now well-worn critique.

“If you are fed up with Washington, the question you ought to be asking is who is willing to take on Washington?” Cruz said. “For 40 years, he's been sitting at that table using his money to buy influence, supporting liberal Democrats.”

But Cruz also passed up a chance to attack Trump for a lack of specificity and similarities to Hillary Clinton: “I will let Donald speak for himself,” he said.

Rubio had his best moments talking Cuba policy – a hometown favorite of an issue – and pounced on Trump’s comments about Islam. “He says what people wish they could say,” the Florida senator said. “The problem is presidents can’t just say what they want.”

Kasich played the role he has consistently, only he had more space in the pragmatic lane this time. “I know how to do it because I’ve done it, and I’ll do it again,” he said.

What’s being done now, though, is the Trumpification of the Republican Party. Republican National Committee Chairman Reince Priebus assured the crowd just before the debate that the RNC would stand squarely behind the Republican nominee, an extraordinary statement only in that he felt it needed to be uttered at a GOP debate at all.

The path from here won’t be so friendly, of course. When Cruz was asked how he could keep Trump delegates from bolting a contested convention, Trump broke in: “Make me president.”

We’re not there yet, but the Republican Party may give that a shot soon enough.