Many union guys (the ones who aren't being paid to attend the rallies, anyway, like those from SEIU) are only lukewarm about Kerry or are outright Bush supporters. I freeped a Dem rally at a steelworkers union hall yesterday at which several prominent state politicos spoke, and the "crowd" was barely 75, many of whom were Kerry staffers and various other local politicians (
freep report posted at #73 here).
In the IAM-AW, the international leadership is in the tank for the Dems, but the rank and file are quite conservative (aerospace workers, a lot of retired military). Everyone I've talked to where I work is voting for President Bush.