All of the top candidates, Hillary, Obama, Edwards, Richardson, and Biden are all anti gay marriage. Unlike possibly all of the other spouses, Elizabeth Edwards is FOR gay marriage. I really don't see how gay marriage can be used to specifically attack Edwards.
Umm... his wife's for it, so obviously he's secretly for it as well, so obviously he's a fagloving northeastern liberal who's out of touch with the American people. Besides, he ran on a ticket with that wellknown faglover from the fagloving state of Massachusetts.
See? Easy.