poison (one) against (someone or something)
To inspire or manipulate one to take a very negative, hateful, or disdainful view of someone or something. It's like Tommy's new girlfriend has been poisoning him against us—ever since they started dating, he's been turning his back on us. The bitter election ended up poisoning many voters against the democratic process entirely.
poison someone against someone or something
to cause someone to have negative or hateful thoughts about someone, a group, or something. You have done nothing more than poison Gerald against all of us! Stop talking to him! Your negative comments poisoned everyone against the proposal.