I presume you meant ‘chance’, as in zero chance? ... Holding the FBI files, the clinton crime family is never to be underestimated. McCain’s past is not so pristine as voters have been allowed to believe. Anyone under forty probably has no idea what ‘Keating Five’ relates to and the disinformation the sycophantic commie media can mount could be devastating even in layered lies.
Fearing remote “theoretical” chances is not healthy in politics or real life. It’s the domain of fearmongerers...
Or, to venture a few more steps into the twilight zone...
Suppose a couple of his Vietcong captors come forward with some very damning things to say about his behavior and loyalty as a guest of the Hanoi Hilton?
It doesn't have to be even remotely true, for their purposes it would suffice to muddy the waters right before the vote.