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A top aide to two-time presidential candidate Vermont Senator Bernie Sanders said the independent and self-described democratic socialist is likely to consider a third run for the White House if President Biden does not run in 2024. 

"I assume that he would give it a hard look," longtime Sanders adviser Faiz Shakir told CBS News on Thursday. "I don't want to make the judgment for him. Obviously, it would be his choice to make. But I assume that he would want to reevaluate it." 

Sanders, 81, ran for president as a Democrat in 2016 and 2020, losing the party's nomination to Hillary Clinton and Joe Biden, respectively. However, his insurgent campaigns, styled as a "political revolution," drew enthusiastic grassroots support and inspired other democratic socialists to run for Congress, including Squad members Reps. Alexandria Ocasio Cortez, D-N.Y., Rashida Tlaib, D-Mich., and others. 

Were he to win the presidency in 2024, he would be 83 years old upon assuming office. Shakir said Sanders is "very aware that he's older now, and he'd have to make a real judgment about his own vigor and his stamina and his desire and hunger and passion to do this a third time."

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Vermont Senator Bernie Sanders

Sen. Bernie Sanders, I-Vt., walks through the Senate subway after a procedural vote on the Respect For Marriage Act at the U.S. Capitol on Nov. 28, 2022, in Washington, D.C.   (Drew Angerer/Getty Images)

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President Biden and French President Emmanuel Macron share a toast after speaking at the state dinner on the South Lawn of the White House on Dec. 1, 2022, in Washington, D.C.  (Drew Angerer/Getty Images)

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"But if it were an open field? Yeah, I'm confident he would take another look at it and say, 'Do I want to do this or not?'" he added.  

BIden, 80, is the oldest person to ever occupy the White House. Despite his age, he has given strong indication that he will run for re-election, reportedly toasting to his 2024 campaign at a state dinner with French President Macron last week. 

The president's chief of staff Ronald Klain has said Biden will make a final decision about running for re-election shortly after Christmas, and sources have told Fox News the Biden family is "fully" in support of a re-election effort. 

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Donald Trump holds his fist in the air

Former President Trump gestures during an event at his Mar-a-Lago home on Nov. 15, 2022, in Palm Beach, Florida. (Joe Raedle/Getty Images)

Shakir acknowledged that Biden seems likely to run again and said that as Sanders' adviser, he would not prepare for an open Democratic primary. 

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"Personally, I take President Biden at his word and our orbit takes him at his word that he's taking it seriously and presume that he is leaning toward yes," Shakir said. 

On the Republican side, former President Trump has already launched his campaign seeking the GOP nomination for 2024. Other Republicans speculated to jump in the race include former Vice President Mike Pence, former Secretary of State Mike Pompeo, Arkansas Gov. Asa Hutchinson, and former South Carolina governor and ambassador to the U.N. Nikki Haley.