no longitudinal data...
2000 annenberg election survey had 54% of white union members voting for gore, in contrast to 54% of whites as a whole voting for bush (survey had 93% of african-american union members voting for gore, compared to 90% of blacks as a whole)...
2004 peter hart survey done for afl-cio had white male union members voting 21% pts higher for kerry, in contrast to white males as a whole voting 18% pts higher for bush (white women union members voted 35% pts higher for kerry over bush)... mh