I think you are all going for the obvious. The obvious things stated above will, sadly enough, not sway most voters. It takes too much work for average people to comprehend it all. However, something discovered along the lines of his physical health or, more importantly, his mental health, either past or current, would cause a great deal of unease for everyone voting. Most people would back away from any candidate discovered to have a past history of mental instablity or mental illness. Think outside the box everyone.
There was that mysterious psychologist who wrote a letter to the Captain of the first boat Kerry served on. He lived in California and just before kerry reported to that boat there was a gap in her service record with no fitness reports. I followed that psychologist who is not in practice any longer. I wondered about a psychiatric condition of some kind shortly before he was sent on his first boat. Nothing came of it. That could be big.