No and yes
McCain could not win the nomination against an incumbent. Has that ever been done?
His invulnerability sheen isn't even skin deep and he can look terrible at times. The closest comparison would be to Howard Dean.
I would have eliminated the "anyone but" factor so the race would have at least been close.
Incumbency is a powerful thing and anyone that loses a second term deserves to lose. They have either run a weak campaign (Bush I), or they are truly ineffective.
