President Joe Biden sought to reassure Democratic voters who have doubts about whether the 79-year-old should run for re-election, while also saying in an interview that he could "drop dead tomorrow."
Already the oldest president in American history, Biden would be 86 if he served out a second term.
He has repeatedly said he will run for re-election in 2024, even as many Democrats have questioned whether the party should support a younger candidate instead.
A poll carried out by the New York Times and Sienna College in July found only 26 percent of Democratic voters supported renominating Biden for 2024, with age cited as the biggest reason for those opposed.
Joe Biden LEAH MILLIS
Biden sought to reassure Democratic voters who have doubts about whether the 79-year-old should run for re-election Toby Melville
In September, Biden publicly sought out Jackie Walorski, an Indiana Congresswoman who died in a car accident the previous month, seeming to forget that she had passed away.
"I'm in good health. All my, everything physically about me is still functioning well, so you know, and mentally too," the president, who will turn 80 next month, told MSNBC.
Biden said he should be judged based on his current vigor on the job, rather than his age, though he acknowledged the issue is a "legitimate" voter worry.
"I'm a great respecter of fate. I could get a disease tomorrow. I could, you know, drop dead tomorrow ... in terms of my energy level, in terms of how much I'm able to do, I think people should look and say - can he still have the same passion for what he's doing?" Biden said.
"And if they think I do and I can do it, then that's fine. If they don't, then they should vote against me - not against me, they should encourage me not to go. But that's not how I feel."