McGovern. Best presidential candidate of the 20th century.
Yes, he was such a good Presidential candidate that he didn't even bother looking closely enough into the background of his running mate, Senator Thomas Eagleton, who he had to drop from the ticket even before the campaign was really under way.
That Eagleton had received an esoteric treatment for depression is not a valid reason to disqualify him from a ticket. McGovern shouldn't have dropped him (which hurt a lot more than it helped), however that does not diminish from the greatness of what McGovern stood for.