On Thursday, Greg Murphy, a Republican and urologist, accused the president of being “jacked up on something that day”.

“He can’t stand under the lights for that long, and I don’t think he can keep a concept in his brain that long,” he said on Fox News.

Sean Hannity, the Fox News host, has also called Mr Biden “hyper-caffeinated”.

It is not the first time that Mr Trump has demanded that Mr Biden take a drug test.

He claimed that Mr Biden had been “uneven” during the Democratic primaries in 2020. He said he would be “strongly demanding” a drug test before their debates ahead of the race for the White House that year.

“Vice-President Biden intends to deliver his debate answers in words. If the president thinks his best case is made in urine he can have at it,” Kate Bedingfield, Mr Biden’s deputy campaign manager, responded at the time.

“We’d expect nothing less from Donald Trump, who p—-d away the chance to protect the lives of 200K Americans when he didn’t make a plan to stop Covid-19.”

Neither of the two men underwent drug tests in the end.