It's kind of funny that unions are anti-immigrant: I think this (along with their past tendencies to be anti-black, etc) have hamstrung a lot of them. Immigrant laborers and American-born laborers have a lot more in common than not: they should both be pushing for higher-wages, more job availability, and better working conditions. As such, the unions should be embracing, rather than rejecting, new immigrants, and making sure that laws are passed to protect the immigrants' interests (such as eliminating the H1-B in favor of more green cards, say), because they are essentially the same interests.