After more than a decade of dealing with a less-than-responsive Bloomberg administration, the delegate assembly of the United Federation of Teachers announced that it is backing former City Comptroller William Thompson in the mayoral race.

Michael Mulgrew, the president of the union, announced the decision shortly before 6 p.m., saying that Thompson would “not only make a great mayor, but a great partner” for the city’s educators, children and parents.

Thompson, the former head of the old Board Of Education, had a mother who was a school teacher, and he told the union assembly that she would have backed his campaign.

He told the union, “We will make New York City the education city,” and referring to the struggles between the Bloomberg administration and the teachers’ union, promised, “I will not make the politics of division undermine that cause.”

The Democratic candidate has previously called for a moratorium on school closures and said last week that teachers should be reimbursed $200 for class supplies.

Members of the UFT delegate assembly told NY1 before the announcement that it is important for the powerful union to stand behind one candidate.

“I feel as a unified body, we can get the person elected that we feel can do the best for unions, for teachers and the city, not just teachers. So I’m waiting to see what the union comes out with the endorsement,” said a UFT delegate.

The Bloomberg administration had a immediate negative reaction to the endorsement.

Andrew Kirtzman, an official Department Of Education spokesman and former NY1 reporter, referred to Mulgrew when he posted on Twitter, “Congratulations, Bill Thompson. The man on your right lobbied against the sexual predator’s bill. How do you feel about it?”

Earlier in the week, Mayor Michael Bloomberg called the UFT nomination a “kiss of death,” saying that the teachers’ union has made many faulty choices on educational policy.

(NY1)