Joe Biden's campaign team on Sunday hit back at Donald Trump's latest call for the former vice president to be drug tested ahead Tuesday night's first election debate.
“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,” said Kate Bedingfield, Mr Biden’s deputy campaign manager.
The president had earlier tweeted that he would be "strongly demanding a drug test of sleepy Joe Biden" ahead of the upcoming debate, moderated by journalist Chris Wallace.
Mr Trump, 74, has since late August called for himself and Mr Biden, 77, to be tested for performance enhancing stimulants ahead of the Tuesday's clash.
Without providing any evidence - other than that he is "pretty good at this stuff" - Mr Trump first made the Biden drugs claim in an interview with the Washington Examiner.
The president cited Mr Biden's improved performance in the final round of the Democratic primary debates against Bernie Sanders in March, as the reason why he thinks his rival may be taking drugs.
Mr Biden, who reportedly does not drink alcohol, has refused to be lured into the drugs claim trap, a tactic deployed against Hilary Clinton in 2016. But it appears his campaign team could not resist.
“We’d expect nothing less from Donald Trump," Ms Bedingfield added in her response to the president's call, before taking a swipe at his handling of the coronavirus pandemic.
I will be strongly demanding a Drug Test of Sleepy Joe Biden prior to, or after, the Debate on Tuesday night. 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???
— Donald J. Trump (@realDonaldTrump) September 27, 2020
"[He] pissed away the chance to protect the lives of 200K Americans when he didn't make a plan to stop COVID-19.”
Tuesday night's debate is the first of three televised contests in the 2020 race for the White House.
With just over a month to go until election day, the meetings could play a key role in who enters the Oval Office in January.
At the event in Cleveland, Ohio, the candidates will likely be quizzed on the Supreme Court, the coronavirus pandemic, the economy and the integrity of the result of the election.
Mr Trump has repeatedly claimed that the only way Mr Biden can win is if the poll is "rigged".
He has repeatedly claimed, with little substance, that the millions of votes cast by mail due to the pandemic could fall foul to voter fraud.