turn against

verb

turned against; turning against; turns against

1

: to stop supporting or being friendly to (someone or something)

The senator eventually turned against the war.

She turned against her best friend.

2

: to cause (someone) to stop being friendly toward (someone)

He tried to turn our friends against us.

3

: to use (something) in a way that harms or discredits (someone)

Her political opponent tried to turn her many years of experience in Washington against her.