Mayor Bloomberg speaks at a press conference this afternoon in Union Square.

The city canceled meetings with the teachers and principals unions today as its lawyers prepare to seek a restraining order against a ruling that reverses thousands of hiring decisions at 24 struggling schools.

Both the United Federation of Teachers and the Council of School Supervisors and Administrators planned to meet with city officials this afternoon to figure out what would come next for the schools, which had been slated to undergo an overhaul process called “turnaround.” The process involved radically shaking up the schools’ staffs, which total more than 3,500 people. But the arbitrator’s ruling undid all of the changes.

UFT President Michael Mulgrew said the meeting was already on his agenda by Friday afternoon, just hours after the arbitrator ruled that the city’s staffing plans for the schools violated its contracts with the unions.

A main agenda item would have been figuring out a mechanism for staff members who were not rehired at the schools to reclaim their positions. Another issue, Mulgrew said on Friday, was whether the city and unions might instead try to hash out a teacher evaluation agreement for the 24 schools so they could undergo less aggressive overhaul processes and still qualify for federal funding.

But this morning, the city told the unions that the meetings were off.

Mayor Bloomberg explained this afternoon that he thinks the city should not have to abide by the arbitrator’s ruling until the arbitrator explains his reasoning.

The arbitrator, Scott Buchheit, released only his conclusions, not the legal rationale he used to get there. That would come separately, he wrote. The city and unions agreed to fast-track the arbitration, which was binding, on the grounds that schools would be harmed if hiring decisions were not made before the end of the school year.

“I have no idea what was going through the arbitrator’s mind,” Bloomberg said after a press conference about a city greenmarket initiative.

“I can just tell you, there are 24 schools, [and] almost all students there are minorities, single-digit-proficiency levels,” Bloomberg said. “These kids, if they’re there for one more year, will never recover in their entire lives.”

City lawyers are preparing papers to present to a judge as early as this afternoon — but more likely tomorrow — that will make Bloomberg’s case.

The lawyers are not at all assured success: They will be seeking a restraining order in New York State Supreme Court, the same court that urged the city and unions into the binding arbitration in the first place. Plus, they will be asking to put on hold the results of a refereeing process the city willingly entered, with a referee that the city and union both approved.

Meanwhile, teachers at the schools are weighing their options. Any teacher who was rehired as part of the turnaround staffing process will automatically keep his or her job, and any teacher who took a job in another school for the fall can choose whether to keep that position or retake his spot at his former school, according to a message from the UFT to teachers at the schools distributed on Friday.

Teachers who weren’t rehired will be able to reclaim their spots and slide right back into the seniority rank they occupied before. Seniority will come into play if the schools lose students and must shed teachers, which contractually must be done according to the principle of “last in, first out” in each subject area.

All of the principals who were in place last week are also entitled to stay on, even if they had been told they would not return this fall. But a handful of principals who left their schools early in the turnaround planning process this winter — including Barry Fried at John Dewey High School and Anthony Cromer at August Martin High School — will not share that right, according to a principals union spokeswoman.

And staff members at the schools are worrying that even if the rehiring reversal stands, the uncertainty that has hung over the schools since last fall will not abate.

A teacher from Long Island City High School who listened in on the hearing where the city and unions agreed to arbitration said at the time that the turnaround schools would be harmed regardless of the lawsuit’s outcome. “It’s like they’re pushing Humpty Dumpty off a wall,” the teacher said. “You will have a lot of trouble putting [the schools] back together again.”

A teacher at Lehman High School said he’s moving on to another school and expects many of his former colleagues to make the same choice. “The administration and principal completely ignored the school these past few months while they planned for next year,” he said. “I believe that it is very likely that our stats went down from last year.”

Among the unanswered questions is whether the nonprofit organizations that had been working with a dozen of the schools will continue to play a role in their operations. The city had hoped to use federal School Improvement Grants to pay the groups, but the grants are almost certainly off the table because the arbitrator’s decision will mean few if any schools meet federal and state eligibility rules.

“Everyone is nervous about what happens next,” said Lisa Jimenez, a teacher at Newtown High School, which has been working with a group called Diplomas Now. “Do we need to worry about getting closed next June? Do we continue with the original plan of these schools having three years to improve?”