SEIU isnt a union but the strongarm part of the Democrat party. Like the brownshirts, they take in the unemployable, give them a uniform, fill them with slogans, tell them they are a vital part of the country, tell them they can do what they want because the union will protect them. They have deep pockets, which is kind of strange because a lot of the members have low paying jobs. They also have no aversion to using violence to acheive their goals.
The SEIU will be THE national union, with all other unions paying homage to it. It will asborb all other unions in the name of unity.