Boring from within

Entryism (also referred to as entrism or enterism, or as infiltration) is a political strategy in which an organisation or state encourages its members or supporters to join another, usually larger, organisation 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 and subversion to hide the fact that they are an organisation in their own right.

The French Turn refers to the classic form of entrism advocated by Leon Trotsky in his essays on "the French Turn". In June 1934, he proposed that the French Trotskyists dissolve their Communist League to join the French Section of the Workers' International (SFIO) and that it also dissolve its youth section to join more easily with revolutionary elements. The tactic was adopted in August 1934, despite some opposition. The turn successfully raised the group's membership to 300 activists.

Proponents of the tactic advocated that the Trotskyists should enter the social democratic parties to connect with revolutionary socialist currents within them, and steer those currents toward Leninism. However, entry lasted only for a brief period: the leadership of the SFIO started to expel the Trotskyists. The Trotskyists of the Workers Party of the United States also successfully used their entry into the Socialist Party of America to recruit their youth group and other members. Similar tactics were also used by Trotskyist organisations in other countries, including The Netherlands, Belgium, Switzerland and Poland. Entrism was used to connect with and recruit leftward-moving political currents inside radical parties.

Since the turn in France, Marxists have used the tactic even if they had different preconceptions of how long the period of entry would last.

In these types of entrism, entrists engage in a long-term perspective in which they work within an organisation for decades in hopes of gaining influence and a degree of power and perhaps even control of the larger organisation.

In entryism sui generis ("of a special type"), Trotskyists, for example, do not openly argue for the building of a Trotskyist party. "Deep entryism" refers to the long duration.

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