According to a forthcoming book, former President Barack Obama chastised his own former White House physician for criticizing Joe Biden’s cognitive health on the 2020 presidential campaign trail.

Rep. Ronny Jackson, R-Texas, writes in his memoir “Holding the Line: A Lifetime of Defending Democracy and American Values” about a stern email from Obama for then-presidential candidate Biden’s “crazy statements and concerning mental gaffes” — a criticism he was uniquely qualified to make, having served as White House physician to presidents George W. Bush, Obama, and Donald Trump.

“Biden was on TV again, making crazy statements and worrying mental gaffes; he had no idea what state he was in or what office he was campaigning for,” Jackson recalls of the 2020 election season. “He apparently thought at one point that he was running for the Senate and later couldn’t remember what state he was campaigning in. This had been going on for months and was getting worse.”

For years, the media accused Trump of being mentally ill, and in 2018, many commentators mocked Jackson for claiming that a cognitive evaluation Trump had taken revealed that he was in “excellent” mental shape and had “absolutely no cognitive or mental issues whatsoever.”

“Trump never made crazy statements like Biden did almost every day,” Jackson writes in his book, “but these people were jumping up and down, saying, ‘He’s not fit to be president; he needs a cognitive test!'”

When Jackson ran for Congress in 2020, he was irritated by the media’s dismissal of Biden’s cognitive impairment. He retweeted a video of Biden’s “latest cognitive misadventure” with the message: “Remember the cognitive test that I gave @realDonaldTrump? The one he aced! Sounds like somebody else might need some testing done!! Scary!!”

President Obama sent Jackson a “scathing” email just 20 minutes after he tweeted.

“I made a point of not commenting on your service in my successor’s administration, and I have always spoken highly of you both publicly and privately.” “You have always provided excellent service to me and my family, and I have considered you not only a fine doctor and service member, but also a friend,” Obama wrote in the email.

“That is why I feel compelled to express my displeasure with your cheap shot at Joe Biden on Twitter.” It was unprofessional and befitting of the position you once held. It was also disrespectful to me and your numerous friends in our administration. You were the President of the United States’ personal physician as well as an admiral in the United States Navy. “I expect better, and I hope that in the future, you will expect more of yourself,” Obama told Jackson.

Jackson chose not to respond because he was surprised and flustered by the email. Jackson recalls considering calling the former president, but a friend, radio host and conservative commentator Dan Bongino, reminded him that Obama did nothing while Jackson was fighting Senate confirmation to be Trump’s secretary of Veterans Affairs.

“So, upon reflection, I thought, You know what? Screw that guy! I’m not doing it,” Jackson wrote. “I just walked away from it, which was the last time I had any contact with [Obama],” Jackson wrote.

“It’s awfully ironic now, considering [Biden’s mental fitness] is all anyone can talk about, including the liberal media,” Jackson told Fox News Digital.

“Let it be known that, as the White House physician for the last three presidents, I was the first to say that we have a serious problem with this man’s cognitive decline, and he will not serve another four years. I’ve always said that there would come a time when it wouldn’t just be me talking about it, but his own party as well, and sadly, that has proven to be the case. Joe Biden’s cognitive failings are on full display for all to see “According to Jackson.

“Holding the Line,” which chronicles Jackson’s journey to the White House as a navy physician, his relationships with the three presidents that he served, and his early political career at a time when the political Left was determined to destroy him, comes out on July 26.