Trump Clinton debate
Hilary Clinton and Donald Trump GettyImages

Donald Trump has suggested there should be a drugs test for both candidates ahead of the next presidential debate, hinting Hillary Clinton was on some kind of medication during their last showdown.

Speaking at an outdoor rally at a car dealership in Portsmouth, New Hampshire, the GOP nominee said his rival had been "pumped up" ahead of their debate, but appeared to have lost her energy by the end.

"I think we should take a drug test prior to the debate. I do," ABC News reported Trump as saying.

"We should take a drug test prior, because I don't know what's going on with her.

"But at the beginning of her last debate, she was all pumped up at the beginning, and at the end it was like 'oh, take me down.' She could barely reach her car."

Trump's suggestion Clinton was on drugs during the second presidential debate comes a day after he hit out at his Democrat rival for relying too much on her teleprompter after his own malfunctioned during a rally in Charlotte.

Going off-script after the words on his screen became illegible, The Washington Post reported him saying: "You know, it's very funny. I went through 17 professional politicians, top people, and I went without any teleprompters. Then all of a sudden, they said, 'Well now you're running the election, you need teleprompters.'

"They're fine, but it's sort of cooler without it, right? Don't you think? I like it better without it. And it's a little strange when you see this place. I watch Hillary, she's got the biggest pieces of glass. And sometimes they're painted black on the other side, because you see better. And she always just reads off the teleprompter and it's short and then she goes home and she goes to sleep."

The suggestion Clinton "goes home and she goes to sleep" is once again playing into the idea that Clinton may not be well enough to serve as president after she fell ill during the 9/11 memorial in New York City.

Since she was taken ill, with what her medical team confirmed was a case of pneumonia, Trump has made several digs at her stamina - with a pro-Trump ad released this week suggesting the Democrat is too ill to be president.