It depends on if you are talking to the Union leadership or the Union rank and file. The Union Leadership sees the illegals as a source of new dues paying members to fund their corruption and fatten the wallets. The rank and file sees the illegals as job competition. The Union Leadership has been shafting the rank and file for a long time and they must kind of enjoy it because they never do anything about it.
Yeah, that's sort of my point in a way. The union members are likely to be more "anti-immigrant" than the union leadership. At some point they'll realize the leadership has a conflict of interest. I grew up in a blue-collar area, and those guys know a raw deal when they see one. Expressions like "sold down the river" come to mind (steel towns always had a river or two).