I thought that I've read in the past where some Democrats with colds or flu have tried to shake Bush's hand (can't recall if this was 2000 or 2004).
There were numerous hippies that tried to lace Richard Nixon's coffee/etc. with large amounts of LSD (Grace Slick was one such agent).
If the election violence from the left is any sign, you can count on them trying this in America.
I knew I like Grace for more than her singing.