Entryism

Entryism

Entryism (also referred to as entrism or enterism, or as infiltration) is a political strategy in which an organization or state encourages its members or supporters to join another, usually larger, organization in an attempt to expand influence and expand their ideas and program. In situations where the organization being “entered” is hostile to entrism, the entrists may engage in a degree of subterfuge to hide the fact that they are an organization in their own right.

via: https://en.wikipedia.org/wiki/Entryism