The first of three highly anticipated presidential debates between President Donald Trump and Democratic nominee Joe Biden begins on Tuesday night, but the two candidates' campaigns are laying down the gauntlet before the stage is even set.

Similar to his 2016 claims about Democratic nominee Hillary Clinton during that campaign, Trump is baselessly accusing Biden of taking performance enhancing drugs.

Trump publicly called for a drug test of both candidates ahead of the debate.

In the past, Trump has used Biden's improved debate performances in the later stages of the Democratic primary to claim that this improvement was due to drugs.

Biden himself was asked about the demand, but—through laughter—declined to comment.

When asked to respond to Trump's demands for Biden to take a drug test, Biden's campaign minced no words.

Kate Bedingfield, Biden's deputy campaign manager, said:

"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. We'd expect nothing less from Donald Trump, who pissed away the chance to protect the lives of 200K Americans when he didn't make a plan to stop [the virus]."

People applauded the no holds barred response.

Meanwhile, Trump's calls for a drug test largely backfired, with some of his critics accusing him of projection.

The first presidential debate will air Tuesday night at 9 pm on every major news channel.