[Toboe]

>There is no box to check on the ballot for "I'm really sure, so count my vote twice!"

Besides what sibling comments said:

But there is the option of not voting/voting implausible 3rd candidate because screw the main 2.

So theoretically you could have non-influenced reps staying at home, because they dislike both candidates.

Or have influenced dems vote Bernie (or don't vote) because Hillary just isn't good enough, when without influence they'd have pinched their nose and voted Hillary.

Or if you don't insist on it being about who wins, you could imagine it about the loosing side being so riled up, that they hinder the winner and turn the winner into a lame-duck president.