"Fellow traveler" is a term for a sympathizer of a cause (generally communism) who is not a bona fide party member https://en.m.wikipedia.org/wiki/Fellow_trave

"Fellow traveler" is a term for a sympathizer of a cause (generally communism) who is not a bona fide party member https://en.m.wikipedia.org/wiki/Fellow_traveller https://en.m.wikipedia.org/wiki/Fellow_traveller