a fellow traveller

a fellow traveler

Someone who identifies with or is sympathetic to the aims or ideology of a political movement or organization, but is not a formal or full member of it. Used especially in the 1950s in reference to those suspected of being communist sympathizers. In my grandfather's day, if someone accused you of being a fellow traveler, it was often to derail your career completely. Despite having a mark against him as a "fellow traveler," he still managed to remain at the Hollywood elite.
See also: fellow, traveler
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

a fellow traveller

A fellow traveller is someone who supports the aims of an organization but is not a member of it. Note: `Traveller' is spelled `traveler' in American English. Although something of a critical fellow traveller, Sampson was very interested in the party.
See also: fellow, traveller
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
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