President Donald Trump said that his Democratic opponent, Joe Biden, “probably” uses drugs to improve his performance during the presidential debates. “There’s possibly drugs involved. That’s what I hear,” Trump claimed in a conversation with Fox News host Jeanine Pirro at the White House on Friday, despite any tangible evidence to support his allegation.

Trump went on to say that Biden might not have been the Democratic Party’s nominee if Sen. Elizabeth Warren (D-Massachusetts) had suspended her campaign earlier, which Trump said would have left a stronger path forward for Sen. Bernie Sanders (I-Vermont).

it was also not the first time Trump, 74, has accused Biden, 77, of taking drugs, without evidence, to boost his debate performance. During an interview with Fox News’ Laura Ingraham earlier this month, Trump said of Biden, “He’s on some kind of an enhancement, in my opinion.”

Trump told the Washington Examiner he had noticed a sudden improvement in Biden’s performance in the Democratic TV debates.

Trump and his campaign have also questioned Biden’s mental fitness during campaign rallies and in targeted campaign ads.

But this attacking tactic does not come as a first for the president: Trump similarly questioned former Secretary of State Hillary Clinton‘s mental prowess when he ran against her for the presidency in 2016.

When ABC News World News Tonight host David Muir asked Biden about some of Trump’s comments during an interview last month, Biden responded with a laugh, “Mr. President, watch me.”