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President Joe Biden, Ronny Jackson, President Barack Obama

Former White House doctorRonny Jacksonis alleging thatBarack Obamaonce sent him a stern email after Jackson retweeted a 2020 video that reportedly showed then-presidential hopefulJoe Bidensaying he was a “candidate for the United States Senate.”

“Remember the cognitive test that I gave@realDonaldTrump? The one he aced! Sounds like somebody else might need some testing done!! Scary!!“tweeted Jackson, 55, who served as physician to the president under both Obama, 60, and successorDonald Trump, 76, from 2013 to 2018.

In his upcoming memoirHolding the Line: A Lifetime of Defending Democracy and American Values, out July 26, Jackson reportedly writes that Obama emailed him about the tweet within 20 minutes.

“I have made a point of not commenting on your service in my successor’s administration and have always spoken highly of you both in public and in private. You always served me and my family well, and I have considered you not only a fine doctor and service member but also a friend,” the email allegedly read, per multiple outlets includingCNNandThe Independent.

“That’s why I have to express my disappointment at the cheap shot you took at Joe Biden via Twitter. It was unprofessional and beneath the office that you once held,” Obama added in the email, perThe Independentand CNN, citing Jackson’s memoir.

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Barack Obama (L) and Joe Biden.Patrick Smith/Getty Images

Barack OBama Joe Biden

The former president allegedly called Jackson’s tweet “disrespectful to me and the many friends you had in our administration.”

“You were the personal physician to the President of the United States as well as an admiral in the U.S. Navy. I expect better, and I hope upon reflection that you will expect more of yourself in the future,” Obama reportedly added.

According toThe Independent, Jackson writes in his book of how he felt following the email, “Screw that guy,” referring to Obama: “I just walked away from it, which was the last time I had any contact with [Obama].”

A rep for Obama declined to comment, while Jackson’s office did not immediately respond to PEOPLE’s request for comment.

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Biden has been open about stumbling over words in the past, having spoken freely about his childhood yearswith a stutter.

The former vice president, 79, dismisseda 2020 questionahead of his presidential win about whether he has taken a cognitive test — an issue Trump, 76, pushed into the spotlight while boasting of his mental capabilities and attacking Biden.

“Come on, man,” he continued. “That’s like saying you — before you got on this program, you take a test where you’re taking cocaine or not. What do you think? Huh? Are you a junkie?”

“I am very willing to let the American public judge my physical as well as my mental fitness,” Biden also said at the time.

source: people.com