(William Howell, Professor in American politics, University of Chicago)

"He's going to be 82, should he be reelected, And he --if he serves out the entirety of a second term --will be closer to 90 than he will be to 80. And this raises lots of concerns, justifiable concerns, in my view."

 (Steven Austad, Professor in Healthy Aging Research, University of Alabama at Birmingham)

"Well, he would be setting a record, but records for aging are being set all the time. And I think not everybody has realized that fact that, you know, an 80 year old or an 86 year old today, particularly one that's had a history of good health, is very, very different than an 80 or an 86 year old was 50 years ago."

 (Lori Cox Han, Presidential Studies professor, Chapman University) 

"So they're going to have to rely probably on Kamala Harris quite a bit. They're going to have to rely on, you know, other surrogates, really the next generation of leaders in the Democratic Party. And I suspect that they're going to want Barack Obama out on the campaign trail as much as possible. But then that doesn't exactly leave a lot of confidence in the actual nominee, if Joe Biden can't generate that kind of excitement without calling in the other younger, more, you know, charismatic people within the party."

(William Howell / Professor in American politics, University of Chicago)

 "One more point on this, though: the frontrunner on the Republican side is no spring chicken either. If it ends up being Trump, he will be 78. Should he win in 2024, that would make him the second oldest person to hold the office."

 "But I think more generally that the thing that the Democratic Party is going to need to do is to figure out how to hand the mantle off to a younger generation. And and to the extent that our parties --both parties -- are struggling to maintain their cohesion and to be a force for good in disciplining our politics, that's going to be increasingly strained to the extent that they're seen as being the party of the very old."