Legend has it that LBJ, in one of his early congressional campaigns, told one of his aides to spread the story that Johnson's opponent fucked pigs. The aide responded "Christ, Lyndon, we can't call the guy a pigfucker. It isn't true." To which LBJ supposedly replied "Of course it ain't true, but I want to make the son-of-a-bitch deny it."
Today's Democrats could learn a lesson from this. The Repukes did.