Facing a fierce backlash within his own party, Donald Trump sought to rally Republicans to his side Sunday night with a scorching debate attack on Hillary Clinton, suggesting he would seek to criminally prosecute his political foe if elected president.
Clinton, standing just a few feet away, responded by saying that a tawdry videotape of Trump boasting about groping women showed his true nature and proved he was resoundingly unfit to serve as commander in chief.
The series of acrimonious exchanges, which began moments into the 90-minute session and rarely let up, resulted in the nastiest and most personally vicious presidential debate of modern times.
Clinton accused the GOP nominee of waging an unremitting series of attacks in his campaign — against Latinos, African Americans, women and veterans, among others — and said he should be ashamed of his efforts to delegitimize President Obama by suggesting he was not a U.S. citizen.
"He owes the president an apology, he owes our country an apology, and he needs to take responsibility for his actions and his words," Clinton said.
"The thing you should be apologizing for are the 33,000 emails you deleted," Trump shot back, referring to correspondence on Clinton's personal email server that was erased before federal investigators could review it.
"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," Trump said.
"You should be ashamed of yourself," he continued, stabbing a finger toward the Democratic nominee.
"It's just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country," Clinton replied.
"Because you'd be in jail," he shot back.
The insult-filled evening came amid a near-mutiny within the Republican Party as the presidential contest increasingly seems to be slipping beyond Trump's grasp.
Before an audience certain to be in the tens of millions, the GOP nominee faced his first public grilling over the 2005 video.
He repeatedly said he regretted what he described as "locker-room talk" and sought to move on by suggesting it was time to discuss more important and "much bigger things."
But Clinton seized on the tape, as Trump scowled, calling it definitive proof of his flawed character. "It's clear to anyone who heard it that it represents exactly who he is," Clinton asserted.
Trump then wheeled on Clinton's husband, Bill, saying no one in American politics had ever been more abusive toward women than the ex-president, who was impeached for lying about an affair with a White House intern.
Trump suggested Hillary Clinton aided and abetted her spouse and, as she glared, called her conduct disgraceful.
With more than two dozen Republican lawmakers and other party leaders rescinding their support since the video surfaced Friday, Trump faced a political crisis unlike any candidate has faced in recent memory.
Apart from his passing apology he showed little contrition, however, for his lewd and predatory statements on the tape and instead used it as the pretext for a long-threatened attack on Bill Clinton and his personal behavior.
In a surprise sprung 90 minutes before facing his rival, Trump appeared near the St. Louis debate site alongside several women who have accused Bill Clinton of sexual misconduct over the years and one who has a decades-old grievance against Hillary Clinton. They expressed their support for Trump and condemned the former president and his wife.
Afterward, they sat with Trump's family as guests inside the Washington University debate hall.
While loaded with personal attacks, the debate did include some discussion of issues — which resulted, in one jarring moment, in Trump repudiating a view held by his running mate, Indiana Gov. Mike Pence.
ABC's Martha Raddatz, a co-moderator, pressed Trump to explain his strategy for ending the humanitarian crisis in Aleppo, Syria, with little success. When Trump seemed to praise Syrian President Bashar Assad as well as Russia and Iran for aggressively fighting Islamic State, Raddatz reminded Trump of Pence's suggestion that Russian provocation needed to be met by American leadership.
"He and I haven't spoken, and I disagree," Trump said.
Turning to healthcare, Trump repeated his vow to repeal the Affordable Care Act passed under Obama and replace it with something cheaper and more efficient — though he provided scant details.
Clinton promised to preserve Obamacare, as it is widely known, and work on improving the federal program
"Let's fix what's broken about it," she said. "But let's not throw it away and give it all back to the insurance companies."
"Everything's broken about it," Trump responded. "Everything."
The two also differed over taxes, with Clinton describing Trump's proposed tax cut plan as a giveaway to affluent Americans like himself.
"Donald always takes care of Donald and people like Donald," Clinton said, insisting she would raise taxes on corporations and the wealthy but spare the vast majority of Americans, those who make less than $250,000.
Clinton faced her own difficult questions from Raddatz.
A trove of internal campaign emails posted Friday by WikiLeaks revealed details of the lucrative speeches the former secretary of State delivered behind closed doors after Clinton left the Obama administration in 2013.
In one excerpt, Clinton spoke of the need to maintain "both a public and a private position" on politically difficult issues. Asked if that amounted to condoning two-faced behavior, a smiling Clinton said she was actually referring to Abraham Lincoln and his actions, as portrayed in the Steven Spielberg biopic, to pass legislation abolishing slavery.
A sarcastic Trump said Lincoln never lied. "That's the big difference between Abraham Lincoln and you," he said, pointing across the debate stage.
Apart from their differences on issues, the debate also showed a contrast in styles.
While Clinton remained largely collected, a glowering Trump roamed the stage and frequently interrupted his rival. Several times he chided the moderators for what he considered to be their unfair treatment.
"One on three," he complained at one point when co-moderator Anderson Cooper of CNN cut off a discussion of Clinton's emails.
The session bookended a disastrous stretch for Trump, which started with an ill-tempered and erratic performance in the candidates' first debate Sept. 26.
He all but admitted his failure to pay federal income taxes and was confronted with derogatory and sexist remarks he leveled at a former Miss Universe, whose transgression was adding a few pounds during her reign.
Rather than back off, Trump waged a days-long shaming campaign against the former pageant queen, Alicia Machado, which was quickly overshadowed when the New York Times obtained a copy of part of his 1995 tax return and reported he claimed a loss of $916 million — enough to allow Trump to avoid taxes for up to 18 years.
He defended his actions Sunday night, saying all he did was take advantage of the opportunities afforded under the federal tax code.
Unlike the first matchup, in which the candidates stood behind lecterns and fielded questions from a lone moderator, Sunday's session was styled after a town-hall meeting, with members of the audience asking questions along with the two journalists.
The candidates took starkly different approaches when a Muslim American woman asked about her worries about Islamophobia.
"Whether we like it or not, there is a problem," Trump said, suggesting Muslim Americans have a responsibility to help fight terrorism by monitoring their community. "We have to be sure that Muslims come in and report when they see something going on."
Clinton responded with seeming agreement on that point, saying that in her discussions with Muslim leaders across the country they have agreed that Muslim Americans need "to be part of our eyes and ears on the front lines."
But to do that, Muslims need to believe they are respected, she added, while condemning the "demagogic" rhetoric from Trump that also threatens U.S. alliances with Muslim-majority countries in the war against the Islamic State extremist group.
"It is a mistake, and it plays into the hands of the terrorists," she said.
Asked directly if he stood by his plan to bar Muslims from immigrating to the United States, Trump said he was proposing "extreme vetting."
As the vituperative session finally wound to a close, a questioner in the audience asked whether either candidate could name one positive trait they respected about the other.
Clinton heaped praise on Trump's children. "His children are incredibly able and devoted, and I think that says a lot about Donald," she said. "I don't agree with nearly anything else he says or does, but I do respect that."
Trump responded with a rare compliment. "She is a fighter. I disagree with much of what she's fighting for … [but] she does fight hard and she doesn't quit and she doesn't give up."
Clinton and Trump were scheduled to face each other in their third and final on Oct. 19 in Las Vegas. Election day is Nov. 8.
Barabak reported from San Francisco, Halper from Washington and Memoli from St. Louis.
8:55 p.m.: This story was updated with more comments from the debate.
7:35 p.m.: This story was updated with details from the debate.
5:30 p.m.: This story was updated with Donald Trump's appearance alongside several women who have accused Bill Clinton of sexual misconduct in decades past.