It's unleashed a new campaign, claiming Mayor Bloomberg has failed as an education mayor.
The union is spending $1 million on TV commercials and newspaper ads.
The ad will reach about 8 and a half million viewers.
It is the latest shot fired in this ongoing battle between City Hall and the Teachers Union over new report cards on teachers.
"10 years as mayor and Mike Bloomberg still doesn't get it," The UFT advertisement says.
It is a brutal ad paid for by the Teachers Union which is now furious at the mayor for trying to layoff bad teachers, and for walking away from negotiations on new teacher evaluations.
"It's not about politics. It's about the schools and the kids so that's what the ad says. Stop it!" said Michael Mulgrew, the UFT President.
Wednesday, the union's president said it's the mayor and not the union standing in the way of teacher evaluations.
"We've had budget cuts for years. We've had a mayor who doesn't understand education, pushing ideas on us. And now we feel completely disrespected and they're quite angry," Mulgrew said.
Tuesday in Albany, the mayor said he hasn't seen the ad and he grew testy when asked about negotiations.
"Any negotiations we've had with UFT we certainly would not talk about. I don't know why you just assume things all the time," Bloomberg said.
City schools could lose hundreds of millions of dollars if the teacher evaluation fight isn't settled soon.
The squabble could tarnish what Bloomberg hopes is his legacy as the education mayor.
"This mayor has invested more time and energy and money in education than anyone who came before him and the only thing that would stymie that is a recalcitrant, stubborn, obstreperous union that doesn't look at the facts," said William Cunningham, Former Bloomberg Communications Director.
In the meantime, negotiations are stalled between City Hall and teachers, and those ads, they just keep running.
"Mayor Bloomberg let's be honest, if you really want to do right by our kids you'll work with teachers and parents and stop playing politics with our schools," the ad said.
The mayor's office Wednesday put out a statement.
Part of it reads, "While the UFT focuses on political stunts and lobbying to keep bad teachers in the classroom, the mayor and governor are working together to implement a rigorous teacher evaluation system."
The UFT has said it welcomes the governor's intervention, but the fight goes on.
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