From Longman Dictionary of Contemporary Englishcard-carrying membercard-carrying memberMEMBERsomeone who has paid money to a political organization and is an official and active member of it a card-carrying member of the Labour Party → card-carrying
Examples from the Corpus
card-carrying member• How many of the extra women on the list are card-carrying members of the Conservative party?• George Spachtholz has been a proud, card-carrying member of the Loyal Order of the Moose for 45 years.• As a card-carrying member of the Wilderness Society, I do not advocate less pristine forest. 