Crypto-communism

Crypto-communism is a secret support for, or admiration of communism. An individual or group keeps this support or admiration hidden to avoid political persecution or political suicide.Crypto-Bolshevism is synonymous, asserting secret Bolshevism.

In the United States, the labels of crypto-communist and crypto-fascist have often been pejoratively applied by political opponents, implying that anyone who supports a particular policy must be secretly extremist.

...
Wikipedia