There are two options for change-- electoral and armed uprising. An armed uprising would not work. The Union is more powerful now than they were during the Civil War. Think "Mark of the Beast" type circumstances. All electronic means of payment would be stopped for uprising participants. Cash would run out quickly and they'd be forced to surrender.
Electoral change will occur more simply-- just get people elected. Drag voters to the polls and make them vote. Go door-to-door to talk to people and convert them to our side. Politicians only care about getting elected. They'll support whatever gets them the most votes.