As I understand things the alt-right are too new to be blamed for much yet. They are not in opposition in the sense they caused much bi-partisan rifts, they seem to actively dislike the tea party - who have been the reflex oppositional political force.
They are this guy
and the people who admire him. Dis-affected, trollish, they believe there is no truth anymore. Trump is ideal for them because he has no beliefs either. They are modern version of 70s punks doing things for lols and the camera, while the establishment looks on, horrified. They live for publicity and shock value. If they get real political power they probably would tear each other apart arguing about what to do with it.