"mud slinging"
The race was close and [Lyndon B Johnson] was getting worried. Finally he told his campaign manager to start a massive rumor campaign about his opponent’s life-long habit of enjoying carnal knowledge of his own barnyard sows.
“Christ, we can’t get a way calling him a pig-fucker,” the campaign manager protested. “Nobody’s going to believe a thing like that.”
“I know,” Johnson replied. “But let’s make the sonofabitch deny it.”
the LBJ campaign never formally denied the story.