Time to stop bringing in the union aspect to it... They may have helped fund campaigns but they don't do much to get out the vote. Honestly, they don't.. It's not the 1980's anymore.
The vast majority of voters have no idea who to vote for. When their employer or union endorses a candidate, they have little reason to vote for anyone else unless they spend the time necessary to learn more about all candidates than a tag line printed in the TC.