Donald Trump and Hillary Clinton hold back-to-back rallies a day after their bruising head-to-head

Mr Trump reiterated his pledge to appoint a special prosecutor to investigate Ms Clinton's private email server if he is elected president

Donald Trump whips up the crowd at a campaign rally in Ambridge, Pennsylvania ((Getty Images))

Less than 24 hours after a debate that has been variously described as the “nastiest”, “lowest”, “ugliest” and “most poisonous” in presidential history, Republican nominee Donald Trump told supporters at a rally in Ambridge, Pennsylvania that he thought the televised clash had been “amazing,” adding: “We had a lot of fun.”

Hillary Clinton, who also returned to the campaign trail on Monday with an appearance at Wayne State University in Detroit, was more equivocal about the bruising experience. “Did anybody see that debate last night?” asked the former Secretary of State. “Well, you never saw anything like that before.”

On the stump, Mr Trump, who at the debate in St Louis had described Ms Clinton as “the devil” and pledged to put her “in jail” should he win the White House, reiterated his vow to appoint a special prosecutor to investigate her private email server. “Special prosecutor here we come,” he said. “If I win, we’re going to appoint a special prosecutor.”

The Republican also continued his attacks on both Ms Clinton and her husband, Bill Clinton, as it emerged that the Trump campaign had hoped to force the former president to come face-to-face on the debate floor with three women who have accused him of rape or sexual assault. Ms Clinton, Mr Trump insisted, had “hatred in her heart.”

The consensus among pundits appeared to be that the Democrat defeated Mr Trump in the debate, but that Mr Trump defeated his low expectations – and neither did much to increase their potential share of the vote. Despite the no-score draw, however, both candidates were triumphal in their recapping of the previous evening’s events.

“Donald Trump spent his time attacking when he should have been apologising,” said Ms Clinton in Michigan, referring to the recent release of a 2005 video in which Mr Trump can be heard boasting about “grabbing” women “by the p****,” comments the mogul repeatedly dismissed at Sunday’s debate as simply “locker room talk.”

She also cited comments from Warren Buffett, a Clinton-backer whom Mr Trump accused of taking a “massive” tax deduction, similar to the $916m deduction revealed in pages of Mr Trump’s 1995 tax return recently leaked to the New York Times. On Monday, Mr Buffett released a statement rebutting the property developer’s claim.

The multi-billionaire investor said that in 2015 he paid almost $1.9m in income tax from an adjusted gross income of $11.6 million, after claiming roughly $5.5m in deductions, almost $3.5m of which were related to charitable contributions. “He agrees with me that rich people ought to be paying more federal income taxes, to pay their fair share for our country,” Ms Clinton said.

Meanwhile in Ambridge, Mr Trump returned to his familiar arguments on trade and manufacturing, saying, to loud cheers, that “China had so much to do with the killing of the steel industry in Pennsylvania.” In fact, a recent Newsweek investigation found, Mr Trump himself used Chinese steel in at least two of his three most recent major construction projects.

As Ms Clinton pointed out the debate and again at her rally, that decision came at the expense of US steel manufacturers in states such as Pennsylvania and Michigan. Mr Trump, she claimed, “went to great extremes to hide the fact that he chose to support Chinese workers, not American workers.”

Such arguments may be academic, given that Ms Clinton is ahead in polls by an average of 8.6 points in Pennsylvania and seven in Michigan. It was also reported on Monday that House Speaker Paul Ryan, the GOP’s nominal leader in Washington, had resolved to cease supporting Mr Trump and focus instead on down-ballot races in hopes of holding on to Congress.

But Mr Trump was apparently undeterred by his plummeting chances of victory, referring to himself, not for the first time, as “Mr Brexit” and insisting that the media and pollsters had it wrong. “Remember I said Brexit was going to happen” he said. “This is like Brexit, folks – you watch.” Watch? They can’t look away.