MSNBC's Jen Psaki defended President Biden's age in a tweet Monday, saying those saying he shouldn't run because of how old he is should consider Donald Trump's seniority as well.

"Just throwing out there. For everyone who is arguing the reason @POTUS shouldn’t run again is because of his age…you know Donald Trump is 76 right?" Psaki posted on Monday. Psaki previously served as Biden's White House Press Secretary.

Psaki's logic drew a mixed reaction online, with some saying she wasn't exactly posting a robust defense of her former boss, who is nearly four years older than Trump. "This isn't the defense you think it is," several users wrote.

Democrats and Republicans have called Biden's age into question as speculation about the 2024 presidential election continues. Biden is turning 80 at the end of November and is already the oldest president in American history. He has repeatedly said he intends to seek re-election.

NEW YORK TIMES SAYS BIDEN'S AGE IS AN ‘UNCOMFORTABLE ISSUE’ FOR WHITE HOUSE, DEMOCRATS AS 2024 PRESIDENTIAL ELECTION LOOMS

Trump would be 78 on election day in 2024 and Biden would be weeks shy of turning 82.

Jen Psaki on Meet the Press

Jen Psaki signed with MSNBC after leaving the Biden administration.  (William B. Plowman/NBC via Getty Images)

"The presidency is a monstrously taxing job, and the stark reality is the president would be closer to 90 than 80 at the end of a second term, and that would be a major issue," Democrat strategist David Axelrod told the New York Times in June.

"Democrats need fresh, bold leadership for the 2024 presidential race. That can’t be Biden," Democratic National Committee member Shelia Huggins also told the Times.

Biden was asked on Wednesday if he had a message for the two-thirds of Americans who don't want him to run for re-election. 

"Watch me," he said to reporters after the midterm elections, where Democrats held control of the U.S. Senate in an unusually strong showing for an incumbent president's party.

President Joe Biden walks toward Xi Jinping

U.S. President Joe Biden reacts as he walks to greet Chinese President Xi Jinping before a meeting on the sidelines of the G20 summit meeting, Monday, Nov. 14, 2022, in Bali, Indonesia. (AP Photo/Alex Brandon) (Associated Press)

BIDEN SAYS HE INTENDS TO RUN FOR REELECTION, BUT POTENTIAL DEMOCRATIC 2024 CONTENDERS KEEP MAKING MOVES 

Biden told MSNBC's Jonathan Capehart at the end of October that questions surrounding his age were "legitimate."

"It could be, I am a great respecter of fate. I could get a disease tomorrow, drop dead tomorrow. In terms of my energy level, in terms of how much I am able to do, I think people should look and see, does he still have the same passion for what he is doing? If they think I do, then it is fine. If not, they should vote against me," he said. 

White House Press Secretary Karine Jean-Pierre laughed off a question about Biden's age and mental fitness in June and told CNN's Don Lemon that it was not a question people should be asking.

"Don, you're asking me this question," Jean-Pierre responded. "Oh my gosh. He's the President of the United States."

WASHINGTON, DC - APRIL 29: White House Press Secretary Jen Psaki speaks at a daily press conference in the James Brady Press Briefing Room of the White House on April 29, 2022 in Washington, DC. During the briefing Psaki took questions on the war in Ukraine and gas prices. (Photo by Sarah Silbiger/Getty Images)

WASHINGTON, DC - APRIL 29: White House Press Secretary Jen Psaki speaks at a daily press conference in the James Brady Press Briefing Room of the White House  on April 29, 2022 in Washington, DC. (Photo by Sarah Silbiger/Getty Images) (Sarah Silbiger/Getty Images)

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Before Biden, Trump held the mark for oldest elected president in U.S. history. He was 70 when he was elected in 2016.