stamp (someone or something) as (something)
To identify, label, or characterize someone or something as a certain type of person or thing. The other kids stamped him as an outsider the moment he joined their class. The opposition was quick to stamp the proposal as nothing more than partisan trickery. Following the war, people who had spoken against the regime were stamped as traitors and jailed.
stamp someone or something as something
to label someone or something as something; to mark someone or something as something. His manner stamped him as a fool. The committee stamped the proposal as wasteful.