New York City’s teachers aren’t usually timid about making contract demands, or apt to shy away from plunging into the political process.

While the principals’ union endorsed a candidate in this year’s mayoral race and released a television advertisement this week bashing the Bloomberg administration for failing to grant school leaders a new contract, the much larger union of public school teachers has refrained from endorsing a candidate and hasn’t bought ad space – or even held a rally – demanding a contract since early June, the second anniversary of their last contract’s expiration.

With the start of the new school year just a week away and the election fast approaching, officials of the teachers’ union said it is holding its fire, waiting for the state’s Public Employment Relations Board to release non-binding recommendations for how the contract dispute should be settled. If the recommendations, which are expected by mid-September, lead quickly to a new contract, it’s likely the union will jump into the political fray, possibly even throwing its support behind Mayor Bloomberg, the Republican incumbent. If the powerful United Federation of Teachers and City Hall remain at an impasse, however, the union is preparing to unleash its fury.

“We haven’t ruled anything out on endorsements. We haven’t ruled anything out in terms of strikes,” the union president, Randi Weingarten, said this week in a telephone interview.

Yesterday, Ms. Weingarten held a closed-door meeting with union members, at which she laid out a game plan for how to proceed if neither regular negotiations nor arbitration yields a contract soon.

“In the last couple of weeks, we’ve started planning for all exigencies,” Ms. Weingarten said.

In the spring, it seemed as though Ms. Weingarten, who is also the chairwoman of the Municipal Labor Committee, was on course to be a kingmaker in the 2005 mayoral election. She was meeting privately with each of the Democrats interested in unseating Mr. Bloomberg, and political analysts said she had the power to bestow upon one of the Democratic contenders three important political assets: votes, campaign volunteers, and inside information.

In June, the teachers’ union ran TV ads and staged a 20,000-person rally at Madison Square Garden demanding a new contract.

After that, however, the union went virtually silent, at least in public, as the state Public Employment Relations Board heard private testimony from the union and the city throughout the summer, and as the two sides continued quiet negotiations. Ms. Weingarten said the union labored throughout the summer to “come up with innovative ways of dealing with teacher quality” to answer the concerns of Mr. Bloomberg’s schools chancellor, Joel Klein.

In early July, it looked as if the closed-door sessions were working. Mr. Bloomberg predicted publicly that there would be a new contract with “substantial” raises for teachers by the first day of school. By mid-August, though, Ms. Weingarten said she didn’t expect any quick resolution.

This week, Ms. Weingarten said her strategy is to wait for the state board’s recommendations, and in the meantime to avoid potentially jeopardizing the negotiation process by leaping into the campaign.

“I wasn’t going to give the mayor an excuse for not closing on a contract, and therefore we did not engage in the primary process – or at least did not engage to date in the primary process,” she said. But she added: “Nobody gets when the city is in the best fiscal shape it’s been in for years … and they’re running on the teachers’ records, and yet they don’t want to do a new contract for the teachers. It’s really unfair.”

A spokesman for the mayor, Jordan Barowitz, said, “The fact-finding panel is deliberating, and we continue to have dialogues with the UFT.”

What happens next depends largely on what the Public Employment Relations Board recommends, how the city and the union react, and how urgently Mr. Bloomberg wants to complete a contract before the November election.

The former director of political action and legislation, Norman Adler, at the city’s largest union, District Council 37, predicted that there would be a resolution by November.

“The mayor would like to have as few people as possible opposed to him. The union would like to deliver a contract that is overdue,” he said. “The election is the catalyst for collective bargaining. If there’s any way it can happen, it’s going to happen before the election. Now, it may not be possible. But if it’s possible in any shape, form, or manner, it’s going to happen.”

He said the state board’s findings could give the union or the mayor an excuse for accepting a contract that is not ideal. And Mr. Adler said that if the union and the city agree on the contract, the union might well endorse Mr. Bloomberg for re-election.

“If the mayor’s going to make you look good, why would you want to make him look bad?” Mr. Adler said, adding that teachers seem more likely to vote for Mr. Bloomberg.

The president of the principals’ union, Jill Levy, said while it might make sense for the teachers’ union to shrink from the public eye right now and hold off on making an endorsement, it was best for her union, the Council of School Supervisors and Administrators, to convince the city publicly to offer it a new contract.

“Different unions have different approaches to life,” she said.

Ms. Levy said the public should recognize that the teachers’ union has 130,000 members and “a lot of potential ways in which to push the administration toward an agreement.” In contrast, she said: “We are a union of maybe 12,000, including our retirees. Our power to push the administration is limited by the numbers.”

She added: “It makes no sense to stay quiet. There was absolutely no chance that we were going to support anyone on the Republican side for the endorsement. To sit back and assume if you don’t say anything the mayor’s going to be nice to you … is kind of like a foolish and very naive consideration.”