Former President Donald Trump has been alleging that President Joe Biden might take performance-enhancing drugs before their debate Thursday night, a baseless claim that has been amplified by Republican lawmakers and conservative media.

Trump has demanded Biden submit to a drug test before the event, with the former president saying he would take one, too. The Biden campaign has not agreed to such a test.

“Right now, crooked Joe has gone to a log cabin to ‘study,’” Mr. Trump said at a rally in Philadelphia on Saturday, as he pantomimed quotation marks with his fingers. “He’s sleeping now, because they want to get him good and strong. So a little before debate time, he gets a shot in the a**.”

Trump has been pushing the claim since Biden’s State of the Union address in March, in which Trump found his political rival to be more energetic than he expected in the beginning before “fading fast.”

The former president has even suggested, also without evidence, Biden might have been on cocaine, pointing to an unsolved incident last year in which a small bag of cocaine was found in a locker at the White House.

“He’s going to be pumped up!” Trump said at a different rally earlier this month in Racine, Wisconsin. “You know all that stuff that was missing about a month ago from the White House? … I think it was Joe!”

Asked for comment, the Biden campaign directed Spectrum News to a CNN interview last week with Mitch Landrieu, the campaign’s co-chair. 

“'Don the con' — he’s going to talk trash like that all the time because that’s what he does,” Landrieu said. “The other day, you may remember, he was trying to question our president’s mental acuity and he could not remember the name of his own doctor. So tell President Trump bring whatever he’s got. President Biden will be standing there ready for him.”

Trump’s claims, meanwhile, have been echoed by some of his allies and Fox News as they’ve continued to argue Biden, 81, has experienced cognitive decline.

Rep. Ronny Jackson, R-Texas — the former White House doctor whose name Trump recently flubbed, calling him “Ronny Johnson” — sent a letter Monday to Biden and his physician Dr. Kevin O’Connor — also demanding the president be drug tested before and after the debate.

“We seen recently in his State of the Union address, there was a Joe Biden that came out that was not similar at all to what we see on a day-to-day basis for the past 3½ years,” Jackson told Fox Business on Sunday. “And there’s just really no way to explain that other than he was on something, that they’d given him medication.

“I feel like this is probably what’s going on this week at Camp David. He’s going to be at Camp David for a full week before the debate, part of that is probably experimenting with just getting the doses just right.”

Biden has been at Camp David since Thursday preparing for the debate.

Asked about Jackson’s comments Tuesday, Rep. Eric Burlison, R-Mo., said he agreed. 

“I think that Trump's team should not underestimate Joe Biden and his team's ability to, you know, whether they're going to jack him up on Mountain Dew or whatever it is,” Burlison told Fox Business. 

In yet another Fox Business interview, Rep. Mariannette Miller-Meeks, R-Iowa, said, “We anticipate that for this first debate, he will be on something.”

Fox News host Sean Hannity said on his show last week he expects Biden to be “hypercaffeinated” or “whatever it is” at the debate, adding that he likes the idea of drug testing presidential candidates like athletes and racehorses.

Trump also called for Biden and Hillary Clinton to be drug tested before debates in 2020 and 2016.