Midway through Saturday night’s GOP debate, Ted Cruz made a comment about Donald Trump being immature, which elicited this sarcastic snap-back from Trump: “Yeah, yeah, I know, you’re an adult.” Anyone who deals with five-year-olds will recognize the trope Trump used: It’s the familiar response of throwing an insult back at your foe. “You’re a dork,” one child will say. “I know you’re a dork,” the other will shoot back, “but what am I?” 

It’s a measure of the remarkably transformative effect Trump has had on the entire tenor of the Republican presidential contest that the entire debate felt less like a political discussion and more like a kindergarten meltdown. 

“Donald, you’re not going to be able to insult your way to the presidency,” Jeb Bush lectured Trump in an earlier debate. But increasingly, there’s every reason to think Bush was wrong. Trump’s supreme skills at vituperation have taken him to the top of the polls, and led last Tuesday to a stunning victory in New Hampshire. And his vintage performance tonight—an exercise in pushing the limits which included calling both Cruz and Marco Rubio liars and drawing boos and catcalls from the debate audience, is unlikely to damage his perch high atop of the South Carolina polls heading into Saturday’s primary. 

There’s no better proof of the success of Trump’s tactics than the imitation of his rivals. On Saturday night in South Carolina, with the notable exceptions of John Kasich (who tried with some success to play the adult in the room) and Ben Carson (who remains a strange wraith-like figure sleepily indifferent to everyone else on stage), the other candidates vied to outdo each other in insults. 

Cruz claimed that Rubio was making promises to Latino immigrants in Spanish on Univision that he wouldn’t dare repeat in English. Rubio sassed back: “I don’t know how he knows what I said on Univision, because he doesn’t speak Spanish.” Along the way, Trump also called Cruz was “the single biggest liar on stage,” adding that the senator was “a nasty guy.” But the Rubio-Cruz spat, which seemed as personal as it was political, was matched in its intense juvenility only by the Bush/Trump fight, which seemed to symbolize the level to which Trump has reduced the debate. 

Trump went out of his way to insult not just Jeb Bush but his brother, the former president, who is stumping in South Carolina. Obviously, the war in Iraq was a big, fat mistake,” Trump said. “George Bush made a mistake. We can make mistakes. But that one was a beauty. We should have never been in Iraq. We have destabilized the Middle East. ... They lied. They said there were weapons of mass destruction, there were none. And they knew there were none. There were no weapons of mass destruction.”

To hear the GOP frontrunner disparage the last Republican president was remarkable. Although he had played with these themes before, he had never been so blunt. It was a powerful testament to Trump’s ability to open up the internal fissures of the party.

“I am sick and tired of him going after my family,” Jeb responded to Trump, somewhat weakly. “My dad is the greatest man alive in my mind. And while Donald Trump was building a reality TV show, my brother was building a security apparatus to keep us safe. And I’m proud of what he did. And he has had the gall to go after my brother.”

Trump had a devastating retort: “The World Trade Center came down during your brother’s reign, remember that.”

As Kasich correctly noted, all the insults traded over the night are only good news for Democrats, “I think we’re fixing to lose the election to Hillary Clinton if we don’t stop this.” At another point, Kasich seemed genuinely disheartened and baffled by the sheer childishness of his rivals, muttering, “I got to tell ya, this is just crazy. This is just nuts. Geez, oh, man.” 

David Frum, former speechwriter for George W. Bush, seemed to agree, when he tweeted about the audience booing Trump like he was a wrestling match villain, “And the audience is joining in the bloodbath. Does this look to America like a party ready to govern anything?”

The answer is no: The Republicans don’t look like they are ready to govern anything because they have become Trumpized—i.e., by definition, they have resorted to a childish state of pouting and invective. This is not a party that can govern, but rather needs governing. The GOP candidates desperately need a teacher or a nanny who can step in and say, “Time out, go to the corner until you are ready to play nice.” A moderator isn’t enough.