Grover Cleveland, 22 and 24th president
Cleveland's first presidential campaign strategy was his reputation for honesty. This was especially handy in combating "establishment" candidates from the federal government that everyone thought was corrupt. (Sound familiar?) The tabloid press was as slimy as it now, and a story appeared that Grover had a love child with an unmarried woman. When the story got national attention, it seriously dented his reputation. To his credit, he admitted an affair (but not that he was the baby daddy) and took responsibility for the child. Even though his opponent screwed up worse, Cleveland only barely squeaked by to win.