Here are key moments from the fiery town-hall style presidential debate between Republican Donald Trump and Democrat Hillary Clinton at Washington University in St. Louis on Oct. 9. (Sarah Parnass/The Washington Post)

About 90 days ago, when Donald Trump accepted the Republican presidential nomination, he had a moment of equanimity. As convention delegates chanted “Lock her up!” Trump shook his head no. “Let’s defeat her in November,” he counter-proposed.

It was a very different Trump who appeared at Sunday night’s second presidential debate: on his heels, facing a revolt in his party over a video unearthed by The Post in which Trump boasted about sexually assaulting women. And Trump declared that, if elected, he would subvert the justice system to go after his political opponent.

“I didn’t think I’d say this, but I’m going to say it, and I hate to say it,” Trump began — always a sign that he was about to say something ill-advised. “But if I win, I am going to instruct my attorney general to get a special prosecutor to look into your situation, because there has never been so many lies, so much deception.”

Special prosecutors, of course, are designed to remove political influence from the justice system; Trump was proposing a special prosecutor for the express purpose of punishing a political opponent.

“It’s just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country,” Hillary Clinton replied.

Republican presidential nominee Donald Trump told Hillary Clinton that if he becomes president, he will instruct the attorney general to hire a special prosecutor to investigate her. (The Washington Post)

“Because you’d be in jail!” Trump interrupted.

Sunday night called for contrition from Trump, as his campaign implodes because of his taped performance as sexual predator. But Trump, though turning in a more even debating performance than he did in his debut, does not do contrition.

Before the debate, he lined up women who claimed they were victims of Bill Clinton’s sexual misdeeds and posted a video of their meeting, with poor audio, on Facebook. Sixteen minutes into the debate, Trump invoked Bill Clinton’s infidelities. After 22 minutes, he started interrupting his opponent.

Before long he was pacing, scowling, pursing his lips, shaking his head and hectoring her: “Oh, you didn’t delete them? . . . Oh, 33,000? Yeah. … Oh yeah, what about the other 15,000?”

“Please allow her to respond,” interjected moderator Anderson Cooper. “She didn’t talk while you talked.”

“Yes,” Clinton agreed, “that’s true, I didn’t.”

Republican presidential nominee Donald Trump speaks during the second presidential debate with Democratic presidential nominee Hillary Clinton at Washington University in St. Louis, Sunday, Oct. 9, 2016. (Patrick Semansky/AP)

“Because you have nothing to say,” Trump snapped.

Trump then started arguing with the moderators. “I’d like to know, Anderson, why aren’t you bringing up the emails? I’d like to know.” In fact, the previous question had been about Clinton’s emails, but Trump was petulant. “One on three!” he protested, suggesting Clinton and both moderators were against him.

Trump had his moments Sunday night and hit Clinton in all her areas of vulnerability. But throughout the debate he was a man at odds with everybody — even his running mate, Mike Pence. When moderator Martha Raddatz reminded Trump that Pence had said that Russian provocations in Syria should be met with American strength and the United States should be prepared to strike the Assad regime, Trump replied: “Okay. He and I haven’t spoken, and I disagree.” On the most important foreign-policy issue of the moment.

Trump repeated his grudging apology for the new video of his predatory sexual language, but he repeatedly chalked it up to towel-snapping. “It’s locker room talk, and it’s one of those things. I will knock the hell out of ISIS,” he declared.

As in the previous debate, Trump took some of his trademark detours around the truth, declaring anew that he opposed the war in Iraq and that such claim “has not been debunked” (he gave his approval to the war on Sept. 11, 2002, on Howard Stern’s radio show). He twice declared that “I don’t know Putin”; he previously said “I got to know him [Putin] very well.” When Cooper asked about his middle-of-the-night tweet telling people to check out a sex tape, Trump replied, “no, there wasn’t ‘check out a sex tape.’ ” His exact words in the tweet were “check out sex tape.”

But mostly, Trump was angry, with everybody and everything.

“Why don’t you interrupt her? You interrupt me all the time,” he complained to Raddatz, though Trump had plenty of air time.

And again: “So, she’s allowed to do that, but I’m not allowed to respond?”

And again: “Excuse me. She just went about 25 seconds over her time.”

And again: “You know what’s funny? She went over a minute over, and you don’t stop her. When I go one second over, it’s like a big deal.”

Will arguing with the refs win Trump more votes? Probably not any more votes than he wins by dismissing his aggressive sex talk as locker room banter. But Cooper and Raddatz have reason for concern: If Trump wins, maybe he’ll send a special prosecutor after them, too.

Twitter: @Milbank

Read more from Dana Milbank’s archive, follow him on Twitter or subscribe to his updates on Facebook.