The Not Ready for Prime Time Bush Like Scott Walker, Jeb couldn’t rise to the demands of the national stage.

We’ll begin with what went wrong with the Republican debate in Boulder, Colo., then look at what went wrong with Jeb Bush.

CNBC’s debate moderators have famously come under fire for questions, statements and a tone that were obnoxious. They were. The moderators seemed intent on trivializing the field. When you say, “Candidate A, you have criticized Candidates B and C, turn to them now and tell them why they’re dopes,” you are presenting yourself as the puppet master and them as puppets. They must either attack their colleagues as instructed and look weak, or push back against the moderator in a way open to charges of defensiveness and cynicism. They can’t win. (Though later one did.)

Jeb Bush and Marco Rubio

The worst of friends: Jeb Bush and Marco Rubio during the Republican presidential debate.

There’s nothing wrong with mischief from debate moderators, but this was dumb mischief, plonkingly obvious in its ideological hostility. What’s your greatest weakness? Should fantasy football be regulated? These questions were merely shallow.

To Jeb Bush: “Governor, the fact that you’re at the fifth lectern tonight shows how far your stock has fallen in this race, despite the big investment your donors have made.” Donald Trump uncorking a taunt, right? No! It was moderator John Harwood! He followed up: “Ben Bernanke, who was appointed Fed chairman by your brother, recently wrote a book in which he said he no longer considers himself a Republican because the Republican Party has given in to know-nothingism. Is that why you’re having a difficult time in this race?”

It is very hard to imagine a candidate in a Democratic debate being asked if he’s not doing well because his party is ignorant and vicious. Jeb’s response to being smacked around like this was some vapidity about how “the great majority of Republicans and Americans believe in a hopeful future.”

There was browbeating, and interruptions aimed at forcing a candidate’s thought-train off its tracks:

Since Chris Christie has called climate change undeniable, asked Mr. Harwood, what would he do about it? Mr. Christie said his solutions would not be the usual Democratic ones involving more taxes and more power to Washington.

“What should we do?” Mr. Harwood pressed.

“What we should do is invest in all types of energy, John—”

“You mean government?” Mr. Harwood interrupted.

Christie: “I got to tell you the truth, even in New Jersey what you’re doing is called rude.”

That was a lovely moment. The best belonged to Ted Cruz. “The questions that have been asked so far in this debate illustrate why the American people don’t trust the media. This is not a cage match. And if you look at the questions—‘Donald Trump, are you a comic-book villain?’ ‘Ben Carson, can you do math?’ ‘John Kasich, will you insult two people over here?’ ‘ Marco Rubio, why don’t you resign?’ ‘Jeb Bush, why have your numbers fallen?’ How about talking about the substantive issues the people care about?”

He continued, over a moderator/interrupter: “I’m not finished yet. The contrast with the Democratic debate, where every fawning question from the media was, ‘Which of you is more handsome and wise?’ ”

Again he barreled past an interrupter: “Let me be clear. The men and women on this stage have more ideas, more experience, more common sense than every participant in the Democratic debate.”

Pressed to answer the original question, Mr. Cruz said he’d be happy to. But Mr. Harwood turned to another candidate.

“So you don’t want to hear the answer, John?” Mr. Cruz challenged.

“You used your answer on something else,” said Mr. Harwood, curtly.

He sure did.

I don’t know if fights like this win you anything, but the pushback was deserved, and instructive for future moderators: Be tough, incisive, follow up, dig down. But don’t be a high-handed snot, don’t wear your bias on your sleeve. That helps nothing. Don’t you get that?

To Jeb. He has not succeeded this year, and there is no particular reason to believe he will. Yes, he still has money, but what has money got him so far?

You could see almost all of what wasn’t working in his exchange with Marco Rubio, whom Jeb tried to zing in an obviously prepared attack on missed Senate votes.

“I’m a constituent of the senator,” said Jeb. But he’s not showing up for work. “I mean literally, the Senate—what is it, like a French workweek? You get, like, three days where you have to show up?” He suggested Mr. Rubio resign “and let someone else take the job.”

Well, said Mr. Rubio, you’ve said you’re modeling your campaign on John McCain’s in 2008. “I don’t remember . . . you ever complaining about John McCain’s vote record. The only reason why you’re doing it now is because we’re running for the same position, and someone has convinced you that attacking me is going to help you.”

Mr. Bush began to respond but let Mr. Rubio cut him off: “My campaign is . . . not going to be about attacking anyone else on this stage. I will continue to have tremendous admiration and respect for Gov. Bush. I’m not running against Gov. Bush, I’m not running against anyone on this stage. I’m running for president because there is no way we can elect Hillary Clinton to continue the policies of Barack Obama.”

Mr. Rubio shut him down, just as Mr. Trump had in previous debates.

It’s widely believed among high Jeb supporters that Mr. Trump—“The Gong Show,” as they call him—has kept Mr. Bush from rising. But Mr. Trump isn’t the problem, he was the revealer of the problem: Jeb just isn’t very good at this.

He’s not good at the merry aggression of national politics. He never had an obvious broad base within the party. He seemed to understand the challenge of his name in the abstract but not have a plan to deal with it. It was said of Scott Walker that the great question was whether he had the heft and ability to go national. The same should have been asked of Jeb. He had never been a national candidate, only a governor. Reporters thought he was national because he was part of a national family.

He was playing from an old playbook—he means to show people his heart, hopes to run joyously. But it’s 2015, we’re in crisis; they don’t care about your heart and joy, they care about your brains, guts and toughness. The expectations he faced were unrealistically high. He was painted as the front-runner. Reporters thought with his record, and a brother and father as president, he must be the front-runner, the kind of guy the GOP would fall in line for. But there’s no falling in line this year. He spent his first months staking out his position not as a creative, original chief executive of a major state—which he was—but as a pol raising shock-and-awe money and giving listless, unfocused interviews in which he slouched and shrugged. There was a sense he was waiting to be appreciated.

I speak of his candidacy in the past tense, which is rude though I don’t mean it rudely. It’s just hard to see how this can work. By hard I mean, for me, impossible.