what are the chances he'll have more bad days between now and december?
what are the chances that he's as capable as he is now in 4 years?
How effective is he going to be at exposing Trump's age as a key weakness?
what are the chances that most wavering democrat voters will compare him to a relative in their eighties and stay at home instead of voting?
The only thing keeping him therre is the inability to replace him.
It's not a good look.