Americans and the world watched one of the ugliest presidential debates in recent US history as Donald Trump and his Democratic rival, Hillary Clinton, exchanged charges in a clear attempt by the Republican business tycoon to overcome the disastrous consequences of a leaked tape showing him bragging about sexually assaulting women. The 2005 tape recording that has rocked the race for the White House over the weekend, plunging the Republican Party into crisis, was raised only minutes after the town-hall style debate started Sunday in St Louis, Missouri. Clinton, who considers being the first woman to win the nomination of one of the two major American parties as an asset, refused to shake hands with Trump as soon as she took the stage and only nodded her head while repeating, “Hello, hello.” Knowing that the video tape would likely dominate the debate, Trump tried hard to avoid the subject, repeating his apology to the American people and women, and claiming that he has changed since then. Meanwhile, he sharply attacked Hillary, and her husband, former president Bill Clinton, who was nearly impeached after he was involved in a sex scandal in the late 1990s. “I'm not proud of it,” said the Republican presidential nominee about his 11-year-old comments that surfaced late Friday. “I apologise to my family, to the American people. Certainly, I'm not proud of it. But this is locker-room talk.” The businessman tried hard to change the subject, arguing that it was more important to talk about the threat posed by the Islamic State in Syria and Iraq, which he argued became stronger because of the failed policies of Hillary and US President Barack Obama. Asked three times by co-moderator Anderson Cooper of CNN whether he had kissed or groped women without consent – as he boasted about in the leaked tape – Trump eventually replied: “No, I have not.” Hillary challenged Trump's denials in the video apology he issued over the leaked tape, saying his 2005 remarks “represent exactly who he is” and were in line with how he has denigrated women in comments made during his campaign. “Yes, this is who Donald Trump is,” said the Democratic presidential nominee. “It's just words, folks. Just words,” Trump responded. When the subject was raised again, the Republican candidate counter-punched hard. He referred to accusations of sexual assault and harassment made against former president Clinton by three women. Tensions ran high heading into the debate as Trump signalled that he would raise the accusations in the debate. He held a surprise press conference beforehand with three women who had accused Clinton of sexual misconduct and a woman who was a victim in a 1970s rape case in which Hillary, a lawyer, defended the suspect. “If you look at Bill Clinton, far worse— mine were words and his was actions,” Trump said when he asked whether he was a different man than when he spoke in vulgar terms about women on tape 11 years ago. “There's never been anybody in the history of politics in this nation that's been so abusive to women,” said Trump of the former US president. The billionaire property developer accused Hillary of attacking her husband's female accusers “viciously”. The camera cut away at one point to a poker-faced Bill Clinton in the audience listening attentively to Trump. “I will tell you that when Hillary brings up a point like that and she talks about words that I said 11 years ago,” he said, “I think it's disgraceful and I think she should be ashamed of herself, if you want to know the truth.” Hillary did not address Trump's accusations, citing the words of US First Lady Michelle Obama: “When they go low, you go high.” “If this were just about one video, maybe what he's saying tonight would be understandable, but everyone can draw their own conclusions at this point about whether or not the man in the video or on the stage represents women,” she said. Trump also sharply attacked Hillary over her using a private email for official purposes while secretary of state, shocking watchers by suggesting that if he became president, he would send Hillary to jail. Questioning some of his claims, Hillary said: “It's just awfully good that someone with the temperament of Donald Trump is not in charge of the law of our country.” “Because you'd be in jail,” Trump snapped, eliciting a cheer from the television audience, marking the first time in a modern US presidential election that one candidate threatened to imprison another. Trump, who called his rival “the devil” at another point in the debate, pledged to appoint a special investigator to look into Hillary's decision to delete her emails after she was summoned by Congress. Hillary, meanwhile, chose to repeat her charges that Trump avoided paying taxes. When squeezed on her private email case, she also chose to change the subject and asked the debate's moderator to focus on other issues such as the economy, healthcare and foreign policy. Nearly reviving Cold War rhetoric, Hillary sharply attacked Russia, repeating allegations that Moscow was behind leaked emails where her campaign managers were discussing means to weaken her Democratic Party rival, Bernie Sanders. She also accused Russia of being involved in war crimes in Syria. However, Hillary said she would not send US ground forces to Syria because the US public do not have an appetite for an overseas war. Trump denied he had special connections with Russia, saying the only common thing between him and Russian President Vladimir Putin, whom he earlier said he admired, was that they both wanted to fight Daesh. The two candidates swapped accusations over Trump's criticism of a Muslim-American couple who lost their son in Iraq, with Hillary saying her rival's earlier proposal to ban all Muslims from entering the United States was only helpful to Daesh and other terrorist groups who want to claim the West and Islam are at war. When pressed by moderators to respond to a question on whether he continued to stand by his proposal to ban Muslims, Trump said it's about “extreme vetting” of refugee seekers coming from troubled areas, such as Syria. The two candidates also sparred over recently disclosed emails that showed Hillary telling a Wall Street audience during paid speeches about adopting two different positions — one in private and one in public. Hillary said that her dual position of having two different stances on a policy issue was a reference made to President Abraham Lincoln's skill at using different strategies to force members of the US Congress to pass the 13th amendment abolishing slavery. Trump said that the Wikileaks disclosure of her remarks showed she had been “caught in a total lie” and he ridiculed her reference to President Lincoln. “Now she's blaming the lie on the late great Abraham Lincoln,” he said to laughs from the audience. “Okay, honest Abe never lied. That's the good thing. That's the one big different between Abraham Lincoln and you.” The night ended with an exchange of rare compliments when, after 90 minutes of vicious debate, a member of the audience asked them to name a positive characteristic they respected in the other. Hillary said that she respected Trump's children, saying they were “incredibly able and devoted, and I think that says a lot about Donald”. “I don't agree with nearly anything else he says or does, but I do respect that,” she said. Trump said that he admired Mrs Clinton's fighting spirit. “She does fight and she doesn't quit and she doesn't give up and I consider that a very good trait,” he said. The third and final debate of the presidential campaign takes place in Las Vegas on 19 October — 20 days before Americans go to the polls to vote for their next president.