Biden aides and allies all say he intends to run — and his team has begun quiet preparations for a campaign — but it has often been the president himself who has sounded the most equivocal. “My intention is that I run again,” he told a news conference this month. “But I’m a great respecter of fate.”

To observe Biden at work is to see a leader tap a storehouse of knowledge built up over a half century in public office as he exploits deep personal relationships at home and abroad, his mastery of policy and his familiarity with how Washington works or doesn’t. In short, the wisdom of the aged.

“Voters, they want to know that the people in those positions have the experience, the expertise, and the grounding to make good, sound decisions that are going to serve the country well, but also to be able to have new and fresh ideas that hopefully will push America in a new and better directions,” said Dartmouth College historian Matthew Delmont.

House Speaker Nancy Pelosi’s decision, at age 82, to pull back from leadership and let a new generation rise may spill over into Biden’s thinking and that of his party as Democrats weigh whether they want to go with a proven winner or turn to the energy of youth.

Biden’s flubs have been the stuff of legend throughout his five-decade political career, so sussing out the impact of age on his acuity is a guessing game for “armchair gerontologists,” as Dr. S. Jay Olshansky, an aging expert, puts it.

In the distorted mirrors of social media commentary, every slip is magnified into supposed proof of senility. A moment of silent reflection by Biden in a meeting is presented as the president nodding off. All of that went into Donald Trump’s quiver of falsehoods when he announced Tuesday he will seek the presidency again.

Some allies see Biden’s blunders as an increasing vulnerability in the eyes of voters as he’s grown older.

In an AP VoteCast survey of the electorate this month, fully 58 percent of voters said he does not have the mental capability to serve effectively as president. That was a grim picture of his standing now, not just looking ahead to another potential term. Only 34 percent said he’s a strong leader.

Those findings come alongside notably low approval ratings in league with Trump’s at this point of their presidencies.

Based on a scientific team’s evaluation of their available medical records, family history and other information, the paper further concluded that both men are probably “super-agers,” a subgroup of people who maintain their mental and physical functioning and tend to live longer than the average person their age.

Nothing has changed Olshansky’s mind about either of them.

“I don’t actually consider 80 to be relevant. It’s his biological age that’s more important and there’s a pretty good chance he’s not 80 biologically,” he said. “And we’ve seen nothing in the latest medical records that would change our view from the evaluation that was done a few years ago.”

Biden is already in the club of high achievers for people his age. Unlike 92 percent of people 75 and over in the US, he still has a job, not to mention a mightily demanding one.

And he’s been on a roll. The November elections produced the best result for a president’s party in midterms in decades — despite the poison pill of high inflation — as Democrats kept control of the Senate, narrowly lost the House in defiance of expectations of a rout, and won several competitive governors’ races in key states.

The president also sealed a string of consequential legislative victories in recent months, on climate, infrastructure, health care expansion, military aid to Ukraine and more.

In democracies, where voters are the boss, and in autocracies, where they’re not, plenty of people in power soldier on in their advanced years, even if few are up there like former Malaysian Prime Minister Mahathir Mohamad, who became world’s oldest leader at 92 and is running to get the office back, at 97.

Much of the leadership in the US Congress is over 70, especially Democrats, and so were Biden’s main rivals in the 2020 Democratic primaries and Trump.

Attribute that, in part, to increasing longevity.

“Life expectancy back around 1900 in the United States was about 50,” Olshansky said, “and we added about 30 years” since.