Former President Trump has volunteered to undertake a drug test before Thursday's debate if President Biden agrees.

Trump made the comment on Monday via Truth Social, his proprietary social media platform.

"DRUG TEST FOR CROOKED JOE BIDEN???" Trump wrote in all capital letters. "I WOULD, ALSO, IMMEDIATELY AGREE TO ONE!!!"

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Trump Faith & Freedom

Trump speaks at the Faith and Freedom Coalition's "Road to Majority" policy conference in Washington, D.C. (Reuters/Evelyn Hockstein)

The Trump team has made the hypothetical use of drugs at Thursday's CNN Presidential Debate, a prominent talking point — continuing the former president's longstanding claim that Biden is unable to speak for long periods of time without medication.

Rep. Ronny Jackson, R-Texas, the White House physician-turned-House lawmaker, demanded in a letter last week that Biden submit to a drug test before the debate with Trump.

The former president shared the letter without comment via Truth Social not long after it was published by Jackson.

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President Biden speaking

President Biden delivers remarks during an event in the State Dining Room of the White House. (AP Photo/Evan Vucci)

Jackson made his request for a "clinically validated drug test" in a three-page message to Biden and his physician, Dr. Kevin O’Connor.

"This drug test should be administered both immediately before and after the debate and should include, but not be limited to, performance enhancing drugs," Jackson wrote.

White House Spokesman Andrew Bates has previously responded to Jackson's speculations about Biden's mental health by comparing him to Dr. Nick, a character from "The Simpsons" who is known to have questionable credentials and medical practices. 

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Ronny Jackson at CPAC

Rep. Ronny Jackson, a former White House physician under the Trump administration, speaks at the Conservative Political Action Conference (CPAC) in Orlando, Florida. (Elijah Nouvelage/Bloomberg via Getty Images)

"How should I handle him? Should I be tough and nasty, and just say, 'you're the worst president in history.' Or should I be nice and calm and let him speak?" Trump asked the crowd during his rally at Temple University on Saturday.

Trump told Fox News that he is not worried about Biden’s debate preparations and feels confident in his own ability.

"Well, I think if he prepares, he'll be fine. Then he will forget it within about an hour after preparing. So, we'll see what happens. We'll see what happens," Trump said.

Fox News Digital's Elizabeth Elkind contributed to this report.