I think most people who pay attention knows that the labor unions have not been the Demorats power base for a while. They still get lots of votes from them, but the unions like the blacks have started to figure out that the Demorats are all about Demorats and one one else.
If blacks are figuring it out, their actual voting patterns aren't reflecting it yet. As for the labor unions, in a State like Michigan, they offer organization which is invaluable. Having said all that, as long as trial attorneys appear to be on the same side of the issues as blacks, unions, Hispanics or whomever else, I doubt they will sense a transfer of power in the selection of Edwards.