From the Daily News:
New York's largest city workers union is expected to endorse Controller William Thompson for mayor this week, labor insiders say - a stunning switch from four years ago, when it backed Mayor Bloomberg.
The move would hang in the air as other major city unions - like the United Federation of Teachers and Teamsters Local 237 - decide who to endorse this fall.
...both are...negotiating new contracts right now with Bloomberg, giving him a chance to win their support.
The DC 37 endorsement would be a huge boost for Thompson's underfunded campaign - not just for the volunteers and phone banks it can offer, but for the message it sends to other unions wary of bucking an incumbent mayor.
DC 37 could make its endorsement as soon as Wednesday. A spokeswoman declined to comment.
Bloomberg took a blow from labor last month when the union-backed Working Families Party narrowly voted to endorse Thompson.
The Retail, Wholesale and Department Store Union backed Thompson in that vote, and later endorsed him. The outgoing president of the teachers union, Randi Weingarten, abstained from the vote, which under the party's arcane rules tilted the endorsement to Thompson.
Thompson lists 10 union endorsements on his Web site, Bloomberg has 11, and both campaigns are gunning for more.
The labor grapevine says the International Brotherhood of Electrical Workers Local 3, which backed Bloomberg in 2005 could go for Thompson soon. Union officials did not return calls for comment.
Thompson can't outspend the mayor. He will have a hard time out-organizing the mayor. But when it comes to unions, he has a shot at outmaneuvering the mayor.