smear campaign (against someone)
a campaign aimed at damaging someone's reputation by making accusations and spreading rumors. The politician's opponents are engaging in a smear campaign against him. Jack started a smear campaign against Tom so that Tom wouldn't get the manager's job.
smear someone or something with something
1. to spread or rub someone or something with some substance. Bitty smeared Bobby with mud and made him very angry. You should smear that burn with lotion. He smeared himself with grease and ruined his shirt.
2. to damage the reputation of someone or something by spreading serious charges or rumors. He smeared his opponent with all sorts of charges. The speaker smeared the entire city with his criticism.
smear something on(to) someone or something
and smear something onto spread or rub something onto someone or something. Judy asked Jeff to smear the sun lotion onto her, and he was very happy to do so. she smeared on the lotion. Jane smeared a little on.