Biden, the US's oldest president, turns 80 on Sunday, making him also the first octogenarian in office. He will undoubtedly enjoy moments with family during a brunch his wife Jill will host, a day after his granddaughter is married on the White House South Lawn.

But the president and first lady will soon begin discussing his next steps in earnest, just as polls indicate many Americans are looking for different — and younger — leadership.

Over Biden's objections, House Speaker Nancy Pelosi, 82, announced on Thursday that she would not seek reelection to Democratic leadership next Congress because "the hour has come for a new generation."

Biden has spent a half-century in federal politics and public life, but the hour may not be at hand for him, for reasons that include the former president and now 2024 presidential candidate Donald Trump.

"He knows he can beat Trump," Jim Moran, a former Democratic House member from Virginia, told Insider. "As long as Trump remains a viable Republican candidate, Joe wants to be there representing the values not just of the Democratic Party but of the broad working class of America who don't easily relate to what they feel are the too liberal, too woke urban elitists in the big cities."

If Biden had a sense that the Republican electorate was moving away from Trump toward a different candidate, "that might conceivably influence Joe's decision," he said.

When confronted with questions about his age, Biden likes to say "watch me."

"Somebody said my birthday is coming up, and I said, 'No, that must be somebody else,'" he joked at a political rally this month in New York.

Biden also said on the Willie Moore Jr. Show that he "can't even say that number, 80."

"I'm serious," he said. "I no more feel that than I'd ... get out from behind this desk and fly."

Biden has said he intends to run for office again, though he often adds the caveat that he is a "great respecter of fate." He said he expects to make a decision by early next year.

"This is, ultimately, a family decision," he said during a November 9 news conference. "I think everybody wants me to run… We're going to have discussions about it. And I don't feel … any hurry one way or another … to make that judgment today, tomorrow, whenever, no matter what the — my predecessor does."

Biden has made clear that he considers the twice-impeached president, who is facing investigations at the state and federal levels, and his MAGA followers a threat to democracy. As Trump trashed Biden while announcing his third presidential bid, Biden responded with a video detailing the low points of Trump's record on Twitter, writing "Donald Trump failed America."

Biden's sense of obligation to run for re-election "would be even greater" with Trump in the race, given what he'd be like if re-elected, said a Biden friend and former staffer, who declined to be named to speak candidly. "The obligation would be cataclysmic, existential, monumental," the friend told Insider in an August interview.

Most Democrats and Republicans, including independents who lean toward these parties, don't see Biden or Trump as their party's strongest candidates for 2024, according to a recent Marist poll. And a Reuters/Ipsos poll this month found 46% of Democrats said Biden may not be up to the challenge of running in 2024 while 26% said the same of Trump, who is 76. The poll found 86% of Americans believe the cutoff for serving as president should be age 75 or younger.

Democrats seem more confident in Biden and his leadership than they were before the midterm elections, though the issue of his age will continue to act as a "headwind," Chris Jackson, a senior vice president at Ipsos, told Insider. "There's not a countervailing force from the left saying, 'No, it's great that we have this older gentleman as president' to push against the right, being like 'No, he's too old,'" he said.

On Friday, the progressive "Don't Run Joe" campaign released a birthday greeting for Biden, urging him not to seek re-election. The group, which opposes him on the basis of job performance, says it has begun grassroots outreach in New Hampshire and will expand to other primary states.

But Biden's allies have long said his known ability to defeat Trump can't be overlooked.

"If our focus is on winning, then going with the guy who knows how to beat Donald Trump is a pretty smart play," Sen. Chris Murphy, a Connecticut Democrat, previously told Insider.

Moran, for his part, said, "Age is a state of mind."

"As long as this country is moving forward, doing the right thing at home and abroad, I don't give a shit how old he is," he added.