Here are a few (but not all) of Republican presidential candidate Donald Trump's insults and interruptions during a brutal debate in St. Louis on Oct. 9. (Gillian Brockell/The Washington Post)

Donald Trump on Sunday night went where Republican leaders and those close to him had begged him not to go: into Bill Clinton’s sex life and beyond.

As he took the stage in St. Louis for the second presidential debate with Democratic rival Hillary Clinton, Trump was a candidate in crisis in dire need of a political victory. He was reeling from an offensive videotape in which he brags about groping and forcing himself on women sexually. He faced a GOP revolt of dozens of lawmakers calling on him to quit the race. And he was struggling with worsening poll numbers amid disclosures about his aggressive use of tax loopholes and his feud with a former beauty queen.

The conventional approach — one urged on him by nervous Republican leaders still attempting to stand by him a month before the November election — would be to calm down, focus on his message of change and stay away from the insults and attacks that have landed him in so much trouble in recent weeks.

But Donald Trump does not calm down.

He threw every accusation he could at his Democratic opponent. Following through on earlier threats to do so, Trump accused Clinton’s husband, former president Bill Clinton, of being “abusive to women.” Then he accused Hillary Clinton of having “attacked those same women and attacked them viciously,” along with “laughing” at a 12-year-old rape victim. He gestured to three of Bill Clinton’s accusers, whom he invited to sit in the debate hall.

Trump said Clinton should apologize for starting the birther movement that questioned the birthplace of President Obama, a fringe movement that Trump himself brought into the mainstream. Seconds later, he called her “the devil.” Then he promised to have a special prosecutor investigate Clinton for “so many lies, so much deception” and vowed she would “be in jail” if he was president.

Trump even seemed to blame Clinton for the death of Capt. Humayun Khan — a Muslim soldier killed in Iraq in 2004 whose parents spoke at the Democratic convention — because as a senator she voted in favor of the Iraq War, which he himself also once supported.

He repeatedly accused Clinton of lying, being an “ineffective” senator and making money off her political position. He said she had hate in her heart and didn’t care about those living in inner-city poverty. He reprimanded the moderators when he thought Clinton got too much time to speak and often hovered over her.

When asked in the final minutes of the debate to name one thing about Clinton that he respects, Trump gave her credit for not quitting — something that a growing number of his fellow Republicans have called on him to do.

“I will say this about Hillary: She doesn’t quit. She doesn't give up,” Trump said. “I respect that. I tell it like it is.”

Since the first debate, Trump has jumped from one controversy to another — first, feuding with a former Miss Universe and urging his Twitter followers to look up her sex tape, then responding to a New York Times report about his 1995 tax return that showed he might have avoided paying federal income tax for 18 years and then reacting to a Washington Post report on Friday about vulgar comments he made in 2005 bragging about how he sexually forced himself on women.

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)

Late Saturday, Trump seemed to adopt a new campaign strategy, a “what the hell do you have to lose” one. He tweeted in all caps that he would “never drop out of the race,” then wandered outside Trump Tower for a few minutes to greet supporters, tourists and journalists, seeming to dangerously expose himself to an unscreened public crowd. Then he retweeted two tweets from Juanita Broaddrick, who has accused former president Bill Clinton of sexual assault.

Nearly 90 minutes before the debate was set to begin Sunday, Trump invited a few reporters into a dimly lit conference room at the Four Seasons Hotel in St. Louis for a four-minute event featuring three women who have accused Bill Clinton of sexual improprieties and a woman who decades ago was raped by a man who was then represented by a court-appointed attorney, Hillary Clinton.

“Thank you very much for coming,” Trump said, sitting at a banquet-style table with two women on either side of him. “And these four very courageous women have asked to be here and it was our honor to help them.”

Paula Jones, who accused Bill Clinton of sexual harassment and received a $850,000 settlement in 1998, said that Trump is “not what other people have been saying he’s been, like Hillary.” Kathy Shelton, the rape victim, accused Hillary Clinton of having “put me through something you’d never put a 12-year-old through” and later laughing about parts of the case in an interview.

“You went through a lot,” Trump said.

“Yes, sir. I did,” Shelton said.

“Okay,” Trump said.

Broaddrick — who recanted an affidavit in which she denied being attacked — said “Trump may have said some bad words, but Bill Clinton raped me and Hillary Clinton threatened me.” Kathleen Willey, who has accused Bill Clinton of groping her, endorsed Trump.

The whole event, broadcast on Facebook, lasted just four minutes but it set the tone for the night. Trump and Clinton took the stage without shaking hands.

So as Trump faced debate questions about his comments and sexual assault, he decided to try to win the White House on Bill Clinton’s past.

“If you look at Bill Clinton, far worse,” Trump said. “Mine are words, and his was action. His was what he’s done to women. There’s never been anybody in the history politics in this nation that’s been so abusive to women. So you can say any way you want to say it, but Bill Clinton was abusive to women.”