In an attempt to improve some of the worst schools in the country, Secretary of Education Arne Duncan is offering states four methods of turning around their lowest performers. But New York City officials say the union contract here rules out one of the three —  the so-called “transformation” model — even though it’s the only one that wouldn’t cause teachers to lose their jobs.

The other three methods either turn schools into charter schools, close them down, or force their principals and at least half of the staff to be fired. “Transformation” calls for the principal’s removal, but keeps the school’s staff in place.

Yet crucially, it also requires that schools use students’ test scores as a significant factor in evaluating teachers, that merit pay be put in place, and that teachers whose students don’t show enough improvement be fired. Since New York state law bars principals from using student data in teachers’ tenure decisions and the teachers contract only allows merit pay for entire schools that perform well, not individual teachers, city officials claim they cannot use it.

That’s despite the fact that the city actually wants to use the transformation model at some of the 34 schools on the state’s turnaround list, a Department of Education official said. He mentioned (but did not name) a small group of schools that are improving and have above-average graduation rates despite their overall-poor performance.

The Department of Education official said that transformation would only be a possible option if the United Federation of Teachers overhauls its contract. He said the city had met with the union, but union leaders would not agree to merit pay for individual teachers or linking students’ test scores and tenure.

The union disputed that characterization. “We are willing to talk to them to work out different things,” said UFT Secretary Michael Mendel. “They have never come to us and asked us to work anything out with regard to the transformation model. If they have no desire to work it out, then it’s easy to say the contract is preventing it.”

Mendel would not say what issues the union would consider being flexible about. “But we’re willing to talk about these things in the hope of being able to satisfy the transformation model,” he said.

The current teacher contract has expired, and negotiations between the city and the union to write a new one are stalled.

The DOE has until May 24 to submit its plans for all 34 schools to the State Education Department and those plans will go into effect next school year.