The Atlantic writer Mark Leibovich called on President Joe Biden to not seek re-election in a new opinion piece, declaring the most elderly person to ever hold the White House "too old" to stay on another six years.

"Let me put this bluntly: Joe Biden should not run for re-election in 2024. He is too old," Leibovich wrote.

"As a point of professional comparison, Biden would be enjoying his 15th year of retirement if he had spent his career as a commercial airline pilot, or his 24th year if he had been an air-traffic controller," Leibovich added. "There’s a reason the FAA mandates compulsory departure times for these positions (65 for pilots, 56 for controllers). These are life-and-death tasks that demand peak stamina and mental acuity. The pressure can be crushing, burnout is rampant, and no one wants to see grandpop in the damn cockpit." 

Biden, already the oldest president ever elected, will turn 80 in November and would be 86 at the end of a hypothetical second term. Leibovich quoted one senior administration official telling him he "just seems old."

President Biden

President Biden, already the oldest president to ever hold office, turns 80 in November and would be 86 years old at the end of a second term.  (Photographer: Ting Shen/Bloomberg via Getty Images)

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Leibovich, a veteran journalist and author known for his in-depth profiles, said he felt "impolite" to make such a charge, "especially given the gross Republican smears about Biden being a doddering and demented old puppet." However, he also acknowledged Biden "will sometimes mangle sentences, blank on names, get tortured by teleprompters, lose his train of thought, or not make sense—which is not so abnormal for someone his age."

Democratic questions about Biden's age and calls by some corners of his party to be replaced as standard-bearer in 2024 have gone from murmuring to roaring in recent weeks.

Biden AFL-CIO

FILE PHOTO: U.S. President Joe Biden delivers remarks at the 29th AFL-CIO Quadrennial Constitutional Convention at the Pennsylvania Convention Center in Philadelphia, U.S., June 14, 2022. (REUTERS/Evelyn Hockstein/File Photo)

The New York Times published a report Saturday featuring interviews with dozens of Democratic officials and lawmakers who think Biden may need to be "cut loose," citing his age and questioning his ability to defeat former President Trump a second time. "CBS Evening News" host Norah O'Donnell cited his advanced age in an interview with Biden's sister Valerie Biden Owens in April, and hosts on CNN and MSNBC have also cited the age factor. 

In an interview with CNN, Rep. Alexandria Ocasio-Cortez, D-N.Y., notably would not endorse Biden in a CNN interview on Sunday, telling Dana Bash, "we'll cross that bridge when we come to it." 

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Even left-wing CNN host Don Lemon, seen as one of the more sympathetic media figures to the Biden White House according to Politico, brought up the age issue this week in an interview with press secretary Karine Jean-Pierre.

"Does the president have the stamina, physically and mentally, do you think to continue on even after 2024?" Lemon asked.

Jean-Pierre appeared stunned and said, "Don! You're asking me this question, oh my gosh… That is not a question that we should be even asking. Just look at the work he does. And look how he's delivering for the American public."

Lemon defended questioning Jean-Pierre about Biden's mental fitness during an appearance on "New Day" Wednesday, noting he had trouble following Biden's answers during his Jimmy Kimmel interview a week earlier.

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"I’m not as sharp as I used to be. And the job of President of the United States is a really, really tough job," Lemon said. "I'm sure he's up to the job, but it is my job as a journalist to ask." 

Karine Jean-Pierre

White House press secretary Karine Jean-Pierre speaks during a press briefing at the White House, Monday, June 13, 2022, in Washington. (AP Photo/Patrick Semansky) (AP Photo/Patrick Semansky)

Biden has repeatedly said he plans to run again, and that message was reiterated by Jean-Pierre this week, but Leibovich said the age issue will continue to plague him. He suggested if he didn't run again, he would cement his legacy as an honorable "elder statesman" placing the country before himself.

"The age issue will only get worse if Biden runs again. The 'whispers' are becoming shouts. It has become thoroughly exhausting—for Biden and his party and, to some extent, the country itself. But the question quiets considerably when no one’s calculating how old a president born during Franklin D. Roosevelt’s administration will be in 2028," he wrote.

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A sharp critic of Trump – Leibovich said Biden's most vital act was simply to get Trump out of office – he wrote that a rematch would be unbearable. He added that whoever won the nomination in his place would inject youth and energy into the party, although that would assume someone like Vice President Kamala Harris or Secretary of Transportation Pete Buttigieg earned the spot.