Even if he would end up losing, Biden would still pardon him.
The amount of chemicals keeping Biden alive prevent him from feeling it
Instead of a burst vessel in his eye he just walks around with a hole in his knee saying "listen jack"
Biden melting into the Tar Zombie from Return of the Living Dead and digging open the moderator's skull in a desperate bid for fresh neurons.
So basically the plot of House M.D but the MC is a geriatric patient trying to stay relevant as a failed politician and he gets his own team of lackeys to order around and keep him entertained(read: barely conscious).
I feel Like Trump would try and pull one of those underwear revolvers with two fingers and accidentally drop it, the bullet ricochets off of Chris Wallace's glasses, and then kneecaps Biden. Trump will take full credit, 1d5 chess and all that.
I can already see the NYT piece "In defense of the presidential shootout"
"Biden slowly sinks to the ground, carefully nursing his wounded limb. As the blood oozes out of the bullet hole and onto the floor, a barely audible 'Aww, c'mon man' is picked up by the microphone."
Honestly, if Trump just shot Biden in the face I'm not sure the GOP would allow anything to happen to them. They might remove him... but they might not.
Shoot 'em in the leg!
edit: to the FBI agent reading this, I am quoting Joseph Robinette Biden and not endorsing violence