Trump demands Biden take drug test before or after Tuesday debate

President's latest salvo against opponent's mental acuity

US President Donald Trump has refused to explicitly commit to a peaceful transfer of power after the presidential elections in November. AFP

US President Donald Trump demanded that Democratic candidate Joe Biden take a drug test before or after the pair's first debate on Tuesday, in his latest shot at his opponent's mental acuity.

"I will be strongly demanding a drug test of Sleepy Joe Biden prior to, or after, the debate on Tuesday night," Mr Trump tweeted on Sunday.

"Naturally, I will agree to take one also. His debate performances have been record-setting uneven, to put it mildly. Only drugs could have caused this discrepancy?"

The campaign teams for both candidates on Saturday finalised the conditions for the debate, including forgoing the traditional handshake, and a small audience because of Covid-19 restrictions.

A drugs test was not mentioned. Mr Trump, 74, and Mr Biden, 77, are prone to blunders and gaffes when speaking.

But Mr Trump has spent months denigrating Mr Biden's mental state, and suggested several times in recent weeks that the former vice president may be using unspecified drugs to boost his performance.

Mr Biden has shrugged the claims off, calling for voters to observe the two men together.

"Watch me. Look at us both," he said in August.

On Saturday, Mr Biden said he expected "personal attacks and lies" from the president during the debate, likening Mr Trump to Nazi propaganda chief Joseph Goebbels.

Tuesday's clash in Cleveland, Ohio, the first of three 90-minute debates, will be the first time voters will see the candidates face off against one another.

The moderator for the first debate, Fox News host Chris Wallace, has set topics ranging across the Supreme Court, the pandemic and economic disasters, racism and the integrity of the election.

Mr Trump has been trailing Mr Biden in the polls for the entire year, giving the president added incentive to change the direction of the contest on national television if he can.