According to Nielsen Fast National ratings data, CNN’s Democratic debate averaged 15.3 million total viewers last night. That would make it the sixth-biggest nonsports cable telecast in history. In the 25-54 demographic, the faceoff among White House hopefuls averaged 4.8 million — the most ever for a Dem debate. CNN’s Ashleigh Banfield bragged on-air this morning that her network’s debate drew “a higher number than the season premiere of The Walking Dead.”

So there was clearly a surprising surge of interest in Clinton, Bernie Sanders, Martin O’Malley, Lincoln Chafee and Jim Webb’s first time together on stage.

Here are a few theories why:…

Hillary is a star: Maybe media types underestimate how much of a draw Clinton is. She is a bona fide celebrity, a historic figure and a candidate attempting a comeback after losing to Obama in 2008.

Bernie has a very loyal fan base: When Sanders speaks, his supporters listen. Tuesday night was his biggest time on a national stage yet, and supporters made sure to be there.

Seventy-nine percent of Democratic insiders surveyed said she dominated her four opponents onstage. Fifty-four percent of Republicans said the same.

“Not even close,” an unaffiliated New Hampshire Democrat said. “Hillary crushed it tonight.”

“I think that everyone walked into this debate looking for her to make a mistake, and she didn’t,” an Iowa Democrat said. “On top of that, Sanders’ lack of preparation showed, and O’Malley was trying too hard to look presidential to be effective.”

Marveled a New Hampshire Republican, “She stood out as a leader, charismatic and personal. It may have been an out-of-body experience.”

She was, in short, a man among boys. And that’s why the debate was so important to Clinton. She may have had a rough time as the Democrats’ presidential front-runner, but her advantages in experience and composure were clear when she shared a stage with her rivals for the first time. Vice President Biden, if he was still pondering a run while watching the debate on television, would find the rationale for his candidacy diminishing…

Sanders did not help himself by talking about the economic example of Denmark and proclaiming that he’s “going to win because we’re going to explain what Democratic socialism is.”

Replied Clinton: “We are not Denmark. . . . We are the United States of America. And it’s our job to rein in the excesses of capitalism so that it doesn’t run amok and doesn’t cause the kind of inequities we’re seeing in our economic system. But we would be making a grave mistake to turn our backs on what built the greatest middle class in the history of the world.”

He defended socialism; she defended the middle class. Sanders, and the other men on the stage, didn’t look presidential; she did.

Why did Hillary Clinton win tonight’s Democratic debate? The reason is simple. She’s the only candidate on stage who can win both the Democratic primary and the general election. And with today’s Democratic party, that is no small feat.

The Democratic march to the left is stunning. Having Bernie Sanders play Clinton’s chief foil may excite the left, but, as much as I hate to say it, David Brock is right: The man is unelectable. It’s not just that he’s proposing $18 trillion in new spending and trillions in new taxes. It’s his personal demeanor, which will turn off most Democrats long before it turns off swing voters in the general election. Martin O’Malley may not be as radical as Sanders, but he is certainly to Clinton’s left, and his record in Baltimore and Maryland, where he put many left wing ideas into practice, will be easily attacked by the Republicans…

A skillful opponent could defeat Clinton. But a skillful opponent is exactly what was lacking on the debate stage in Las Vegas. There’s only one other Democrat who could conceivably win both the nomination of his party and the general election. And time for Joe Biden to enter the race is running out.

In the spin room following the debate, Clinton’s allies as well as senior Democrats who have not taken sides in the primary said a debate that is likely to give Clinton a needed jolt of momentum also may have sucked a lot of air out of the Biden balloon. How, they wondered, could Biden now convince donors and other top Democrats now backing Clinton to abandon her and join his campaign?…

“Neither Hillary nor I want to weigh in on the vice president’s decision-making here,” Villaraigosa said. “This is a decision he’s making with his family. But if you’re asking me, ‘Did she look unbeatable tonight,’ the answer is, ‘yes.’ Is she the candidate the Republicans fear the most? The answer is, ‘yes.’ Did she look presidential, calm, deliberate, passionate about the issues? The answer is, resoundingly, ‘yes.'”…

“He needs to make up his mind,” Podesta said of Biden. “She put in a tremendous debate performance tonight and I think that she occupied a space in the party that showed that she was going to fight for this nomination, take the fight to the Republicans, put forward a program that people could really grab onto, believe in, and she was going to fight for the people she’s been fighting for all her life. If he wants to get in and challenge her, then he needs to do that, and that’s his right.”

“I think Biden would be scared to be up there,” one giddy Clinton backer told me in a hallway of the Wynn after the debate. “I don’t see how he gets in,” another said…

Going into tonight, Clinton’s strategy was to make Biden seem “unimportant” by focusing on substance and policy. On those fronts she delivered big, and did much to soothe the fears of her anxious supporters. “I felt that we saw the next president of the United States,” Palmieri said. For Biden, the danger in waiting has always been that the political landscape could shift before he announces. Tonight’s debate shifted the landscape. In recent weeks, the conventional view among Democrats has been that Clinton’s email scandal combined with her inability to connect created a wide opening for Biden to get in (along with the inspirational way he grieved following his son’s tragic death).

The most powerful image Clinton conveyed tonight is that she’s an actual candidate rather than a virtual one. “I don’t take a backseat to anyone,” she declared. “This debate was about these five people,” Benenson said. And, if she aces next week’s Benghazi hearing on Capitol Hill — and many Democrats I spoke to expect she will — then she would have effectively eliminated any remaining arguments for a Biden run. Unless, of course, the ongoing FBI investigation into the security of her email server ends in a bombshell that instantly blows open the door. But for now, Biden looks left out in the cold.

Democratic insiders were nearly unanimous in their adulation of Hillary Clinton’s debate performance Tuesday night. But one notable faction read from a different post-debate playbook: Obama campaign alums…

“Clinton had a great night, but [Bernie] Sanders winning the focus group and online polls, but losing the pundits is reminiscent of Obama in 07-08,” said Dan Pfeiffer, a former senior adviser to Obama, in a post-debate tweet reminding Democrats that Clinton’s perceived invulnerability has collapsed before…

David Axelrod, Obama’s top political strategist, noted that “Clinton made a few mistakes,” and he listed her mischaracterization of her position on the Obama administration’s Trans-Pacific Partnership trade deal, which she claimed she hadn’t fully supported in the past before coming out against it this week.

“That isn’t true and was sloppy, giving her opponents another proof point in their assault on her trustworthiness,” Axelrod wrote in an otherwise praiseful CNN column that posted Wednesday morning.

Bernie won the debate for Hillary. Both had solid performances. But when Bernie said “the American people are sick and tired of hearing about your damn e-mails,” the tension release in the room was palpable. He united the crowd and helped the Clinton campaign turn the page. Back in May, I wrote that Democratic voters wouldn’t let the e-mail controversy rattle them because they have “ Clinton Fatigue Fatigue.” That hasn’t seemed true over the summer, but it sure did tonight, because Bernie made it OK for Democrats to not care.

Hillary was eager to make the pragmatist case against Sanders, pointedly saying she is “a progressive who likes to get things done” and rejecting Sanders’ dream of an America that emulates socialistic Denmark. When she tried a similar contrast with Barack Obama eight years ago, it went poorly. But that was against the backdrop of her Iraq war vote, and against a wilier opponent. It’s true that Clinton has sought to minimize daylight on Keystone and TPP. But these other responses show she doesn’t believe she needs to go outside her ideological comfort zone to win the nomination.

Sanders’s insurrectionism is crucial to his political appeal. Progressives don’t just love him because his policy proposals are more left wing than Hillary’s. They love the fact that he calls America’s political and economic system corrupt, and that he refuses to play by that corrupt system’s rules: for instance, by raising money via a super PAC. That’s why being a “socialist” doesn’t hurt Sanders among many liberals. For many, “socialism” is just another way of saying you want to tear down the existing order and build something better in its place.

But if Sanders’s insurrectionism is key to his success, it may also put a ceiling on it. As angry as many liberals are about economic inequality, the Democratic Party is today in a far less insurrectionist mood than the GOP. Republican presidential candidates routinely bash John Boehner, to wild applause. If a Democratic candidate attacked Nancy Pelosi, liberals would think he or she were nuts. And Democrats still really like Barack Obama.

That’s why, during the debate, Hillary hugged Obama so close. She played to the fact that while Democrats think some big things in America are fundamentally wrong, they also believe their leaders are trying to make things better. Under Obama, in fact, they believe that things have gotten better. One reason Hillary couldn’t beat Obama in 2008 was that after George W. Bush, she didn’t seem to be offering big enough change. But now that she’s running to succeed a president most Democrats like, her inside-the-system, incremental approach enjoys more appeal.

Bernie Sanders, like Donald Trump, can only win if a plurality of primary voters want to turn their country, and their party, upside down. With her performance last night, Hillary Clinton reminded Democrats—in a way Jeb Bush has still not reminded Republicans—why that might not be necessary after all.

Clinton gave about the performance that might reasonably have been expected from a frontrunner who gained a ton of experience as a debater during the 2008 Democratic primary: pretty good. Poised, polished and highly competent at appealing to various segments of the Democratic electorate. But also risk-averse and without all that many high notes.

The media judged Clinton’s night to be way better than “pretty good.” CNN’s Van Jones declared Clinton’s performance to be “flawless” and compared her to Beyoncé. Mark Halperin gave Clinton a perfect A. The New York Times, which has been very tough on Clinton, was full of praise for her.

So you can expect the “Clinton comeback” narrative to prevail over the “Clinton in disarray” narrative — at least for a few news cycles…

[D]eclaring a “Clinton comeback” is a bit like declaring Tom Brady or LeBron James to be the comeback player of the year. Clinton didn’t have anything to come back from; she was winning the nomination race before last night’s debate — by a lot.

The party’s youth base is lining up behind Sanders for one simple reason: They don’t want a coronation, and they don’t want Hillary Clinton. But they are going to come to learn, just as we all did last night, that they are stuck with her. The coronation became evident the second Sanders leapt to defend Clinton from Cooper’s questions about her ongoing e-mail scandal and Wall Street donors. Clinton’s statement that she “represented Wall Street in the Senate” should have sent shivers down every post-Obama progressive voter’s spine, and Sanders’s refusal to call her on it should have been even more terrifying.

On last night’s evidence, the coronation is in full swing. The candidates refused to test Clinton’s shatter-resistance for fear of cracking her, as if she were the party’s antique China doll. Democrats thus find themselves stuck with an oligarch who voted for the war in Iraq and was once “adamantly against illegal immigrants” and gay marriage. An oligarch whose biggest donors are Wall Street’s largest banks. Progressives are either going to have to abandon their populist egos of the past seven years and suck it up, or hope that Biden, not exactly a portrait of vigorous adolescence, comes riding in to save them.