If something came up and he had a very good reason to replace Biden, (like a history of electric shock treatments) he could then probably get away with it. Elsewise, he’s stuck with Biden.
Even then, he'd have a tough time convincing the public that the reason was genuine. It'd likely come across as too suspicious and a *me, too* kind of thing. I think that too many people would suspect him of lying from the start.
I think that the only way he could maybe convince people that it was genuine is if he DIDN'T pick a woman.