US Republican presidential candidate accuses his Democratic rival of being "pumped up" on drugs during debate.
Donald Trump has challenged Hillary Clinton to a drug test before their next debate, suggesting the Democrat was "pumped up" on performance-enhancing drugs.
The attack from the Republican nominee came as he accused "corrupt" media of seeking to rig November’s vote in his Democratic rival’s favour, by reporting snowballing claims of his sexual misconduct.
Trump has trampled all conventions in his treatment of his opponent, vowing if elected to jail her over her email practices as secretary of state - and making "Lock Her Up" a rallying cry for his supporters.
His campaign has actively bruited theories about Clinton’s health, seizing on her bout of pneumonia last month to suggest she is concealing a major health problem, and is unfit for office.
In a new attack, he suggested she had taken drugs ahead their last debate, and called for her to be tested ahead of their final duel Wednesday in Las Vegas.
"I don’t know what is going on with her," Trump, 70, told a rally in Portsmouth, New Hampshire.
"At the beginning of her last debate, she was all pumped up at the beginning. At the end, it was like, ’Take me down,’ she could barely reach her car.
"Athletes, they make them take a drug test. I think we should take a drug test prior to the debate. Why don’t we do that?"
Saturday’s attack on his Democratic rival marked yet another escalation of Trump’s electoral strategy heading into the final weeks of a race that has defied all political norms.
As Trump falls in the polls - abandoned by part of his own camp - he has spent the week claiming the media and a "global elite" are working against him, alleging that Clinton plotted to destroy the sovereignty of the US.
"Hillary is running for president in what looks like a rigged election," he charged in New Hampshire.
"The election is being rigged by corrupt media pushing completely false allegations and outright lies in an effort to elect her president."
Ten women have now come forward to say they were the victim of unwanted advances by Trump.
He vehemently denies the women’s allegations.
For her part, Clinton has scaled back her campaign commitments, keeping a low profile as Trump battles the allegations, set off by the release last week of a video of him bragging about groping women.
But the Clinton camp issued a prompt response to Trump’s latest comments on the election, accusing him of seeking to erode public faith in the vote.
In a statement, Robby Mook, Clinton’s campaign manager, said: "This election will have record turnout, because voters see through Donald Trump’s shameful attempts to undermine an election weeks before it happens."