In 2004, the union endorsed Democratic nominee Mouthzilla.
However, the union wasn't unanimous for Hillary:
One official who attended today’s board meeting said 23 board members had voted to endorse Mrs. Clinton while 10 voted for other candidates or for no endorsement. At the meeting several officials argued against backing Mrs. Clinton, saying that she would have trouble beating a Republican in November 2008 because her negatives are so high.
It's a bad sign. She can't win the general election, and last night's debate gave the GOP plenty of ammo, should she win the nomination.