In the latest NPR Politics Book Club, Danielle Kurtzleben talks with journalist Sasha Issenberg whose book The Engagement chronicles the path of marriage equality from a fringe issue to one of the nation's central civil rights fights. His book explores the complex ways that money and disagreements among activists shape political movements in the United States.This episode: demographics and culture correspondent Danielle Kurtzleben.Connect:Email the show at nprpolitics@npr.orgJoin the NPR Politics Podcast Facebook Group.Subscribe to the NPR Politics Newsletter.Find and support your local public radio station.