United States President Donald Trump on Tuesday claimed that Democratic presidential candidate Joe Biden took drugs to improve his performance in debates, AFP reported. The president repeated his demand for Biden to take a drug test before their first of three presidential debates scheduled for September 29.

“He’s taking something [that] you know, gives him some clarity, or whatever,” Trump told Fox News.

He added that Biden was “a disaster” and “grossly incompetent” at first when there were multiple Democratic candidates on stage. But at a later debate when he faced Senator Bernie Sanders “he was ok”, Trump said.

The president said he is ready to take a drug test before the presidential debates.

Meanwhile, Biden called Trump a “fool” for suggesting that he took drugs to improve his performance. “I’m looking forward to the debate and he’s a fool,” Biden said. “The comments are just foolish.”

At the interview, the US president said since attacks from the Democratic side were gaining in intensity, he will take his “gloves off”. “Joe [Biden] is lost,” said Trump. “We can’t have a president that is mentally lost.”

Trump cited many unintentional remarks made by Biden, believed to be linked to the Democrat’s lifelong struggle with stuttering. The president also pointed out Biden’s reluctance in taking unscripted questions to support his claim.

This is not the first time Trump was making drug-use allegations against Biden. On August 27, the US president had asked his rival Biden to undergo a drug test along with him before the presidential debate, according to BBC.

Trump had made similar comments in the run up to the 2016 presidential elections against his rival Democratic presidential candidate Hillary Clinton, NBC reported. “Athletes, they make them take a drug test,” Trump said at a Portsmouth rally in New Hampshire in October 2016. “We should take a drug test prior to the debate 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...she could barely reach her car.”