A defiant Donald Trump on Sunday said Hillary Clinton would go to jail if he were president and attacked her husband for his treatment of women in a vicious presidential debate less than a month before the U.S. election.

Their debate, the second of three before the Nov. 8 vote, was remarkable for the brutal nature of the exchanges between Trump, the Republican presidential nominee, and Clinton, his Democratic rival.

He called her a "devil" who repeatedly lies, someone with tremendous hate in her heart. She called him an abuser of women.

There was a palpable sense of mutual contempt as they stood on stage, refusing to shake hands at the start. Moderators Anderson Cooper of CNN and Martha Raddatz of ABC both seemed at points to be grimly watching two trains collide.

Through it all, Trump, 70, and Clinton, 68, both landed punches as they clashed over taxes, healthcare, U.S. policy in the Syria civil war and Clinton's comments that half of Trump's supporters belonged in a "basket of deplorables."

Trump took the stage in St. Louis, Missouri, at the most perilous time of his 16-month-old candidacy.

A newly uncovered 2005 video of him making vulgar remarks about women prompted a stampede of Republican politicians to abandon him, deepened fissures with establishment party figures, and seemed to many in the party to put his already uphill battle to win the White House even farther out of reach.


CLINTON 57 PCT, TRUMP 34 PCT

A CNN/ORC snap poll of debate watchers found that 57 percent thought Clinton won the encounter, versus 34 percent for Trump. Asian shares crept higher and the Mexican peso climbed on Monday as markets saw less chance of a Trump victory.

Even after the debate, party leaders remained concerned that Trump had not shown enough contrition over the sexually aggressive remarks to win over independents and women voters who could decide the election.

He again described the comments as "locker-room talk" and said he had never kissed or groped women without their permission, despite having bragged about doing so on the video which emerged on Friday.

President Bill Clinton had done worse to women, Trump said in one of several forceful attacks that may reinforce his popularity with his core supporters who detest the Democratic nominee.

Hillary Clinton responded that Trump's comments showed he was unfit for the White House.

"He has said the video doesn’t represent who he is but I think it’s clear to anyone who heard it that it represents exactly who he is," Clinton said.

She accused Trump of dodging a discussion of policy issues to avoid talking about his campaign because of “the way yours is exploding and Republicans are leaving you."


TRUMP VOWS PROSECUTION

Early in the 90-minute debate, Trump said he would appoint a special prosecutor to look into Clinton's operation of a private email server during her tenure as President Barack Obama's secretary of state from 2009-2013.

Clinton said, "You know it’s just awfully good that someone with the temperament of Donald Trump is not in charge of the law in this country.” Trump shot back: “Because you’d be in jail.”

A nearly year-long FBI investigation into the emails concluded earlier this year without charges being filed, although FBI Director James Comey said Clinton had been careless in her handling of sensitive material.

In a startling admission, Trump dismissed a statement from his vice presidential running mate, Mike Pence, last week in which Pence said the United States should be prepared to intervene militarily in Syria.

"He and I haven't spoken, and I disagree," Trump said.

Pence, already the subject of rumours that he might bolt the Trump ticket in disgust at the lewd video, tried to quell the rumours by praising Trump after the debate was over.

"Congrats to my running mate @realDonaldTrump on a big debate win! Proud to stand with you..." Indiana Governor Pence said.

Responding to an Oct. 1 New York Times story, Trump acknowledged using investment losses to avoid paying taxes, saying "of course I do." The Times reported he took so substantial a tax deduction on a declared $916 million loss in 1995 that he could legally have avoided paying any federal income taxes for up to 18 years.


MOVING FREELY AROUND THE STAGE

The debate's town hall-style format, with undecided voters posing about half the questions and the debate's moderators posing the others, allowed the candidates to move freely around the stage and address the questioners directly.

Clinton and Trump both stood up to answer questions, and Clinton frequently stood directly in front of the questioners to try to connect with voters. At times Trump stood almost over her shoulder, or wandered the stage, while she spoke.

Clinton defended her statement in which she said half of Trump's supporters were part of a "basket of deplorables."

"Within hours I said I was sorry about the way I talked about that, because my problem is not with his supporters, it's with him," Clinton said.

Trump, in a badgering tone, offered a blistering critique of Clinton’s handling of foreign policy as secretary of state, repeatedly calling it a failure.

Taking a breath through his nose with a loud sniff, he said, “The fact is almost everything she’s done in foreign policy has been a mistake and a disaster."

Asked at the end to name one thing each admired about the other, Clinton said she respected his children for their ability and devotion to Trump. In response, Trump called her a fighter and said he admired her for her refusal to give up.

As the moderators announced the end of the debate, the two candidates turned toward each other and shook hands.

Their next and last debate is on Oct. 19.