Texas Rep. Ronny Jackson on Tuesday said he received a “scathing” email from former President Barack Obama for questioning President Joe Biden’s mental fitness.

Jackson, a retired Navy doctor and former White House doctor for Obama and former presidents George W. Bush and Donald Trump, said in a podcast with fellow Republican Rep. Jim Banks that only 20 minutes after he tweeted about Biden’s recent mental mistakes, Obama pinged him.

“He just tore me up,” Jackson said. “An entire page about how disappointed he was in me and how it’s beneath me as a physician and beneath me as an officer in the military to be attacking Joe Biden like this. And it was a betrayal of the trust that he and his administration put in me and he was so disappointed in me.”

Jackson, who is serving his first term in Congress, inisisted that Biden, who at 78 is the oldest-ever president to hold office, continues to show signs of mental stress.

“All I know is that he’s got age-related cognitive decline,” Jackson said. “He is not mentally fit right now. He’s 78 years old and you can see it. You don’t need to be a physician to look at him and to look at his behavior and some of the other stuff, just the way he shuffles away, stares off into space.”

“I know what that job entails, both physically and mentally, and how demanding it is,” he added. “And I can tell you right now, I’m 100% sure that Joe Biden is incapable of doing that job.”

Biden has not released a medical report since 2019 and his administration has deflected questions about his health, according to the Daily Mail.

The president was most recently criticized for appearing to doze off during an event at the COP26 climate summit.

In 2018, Jackson was widely panned by the mainstream media while serving as Trump’s White House doctor when, after giving him a cognitive test, he held a press conference in in which he praised Trump’s “incredible genes” and said “there is no question he is in excellent range” when it comes to his cardiac health, the Daily Mail reported.

“He has incredibly good genes, and it’s just the way God made him,” Jackson said at the press conference. “I told the president that if he had a healthier diet over the last 20 years he might live to be 200 years old,” adding that Trump had a perfect score on the Montreal Cognitive Assessment.