The union for teachers is weighing all its options as a labor dispute drags into its 13th month and schools prepare for the return of students Monday.

"We know that we have some potential legal options," said Joan Lewis, vice president of the Hawaii State Teachers Association. "We’re also looking at our (other) options and where our teachers are willing to go with things."

Lewis said calling a strike authorization vote is one of the possible options the union is looking at, but not the only one.

HSTA’s executive board is set to meet early next month to discuss the union’s next steps.

If teachers did vote to authorize a strike, it doesn’t necessarily mean one is imminent.

So far this summer, the state and HSTA have made no progress toward reaching a deal.

The state is still asking teachers to return to the bargaining table, while the union believes a six-year agreement that teachers had previously rejected then voted to approve in May should be honored.

And since HSTA believes it has an agreement with the state, it is not ramping up for talks on a 2013-15 contract, as other public-sector unions are.

The lack of movement means teachers will continue working under a "last, best and final" offer the state unilaterally implemented on July 1, 2011, when talks stalled. The offer, which includes 5 percent wage reductions and higher health insurance premiums, expires June 30, 2013.

HSTA President Wil Okabe told members earlier this month that he believes the state can — and must — honor the agreement that teachers first rejected then voted to approve.

Okabe said the union may pursue legal means in an attempt to compel the state to honor the agreement.

Gov. Neil Abercrombie, meanwhile, has repeatedly called the agreement invalid and says a new deal needs to be reached at the bargaining table.

Under the agreement, Hawaii teachers would continue to take 5 percent wage reductions through June 30, before moving to a new salary schedule that recognizes their years of service.

The Department of Education would also move to a revised teacher evaluation system linked to student performance. Teachers rated "effective" or higher would be eligible for annual raises.

Neil Dietz, the state’s chief negotiator, said in a letter to Okabe on Wednesday that the union and state must resume talks to hammer out a new deal.

"Nothing precludes the parties from considering the provisions of prior tentative agreements," he said.

With neither side budging for now, there is a possibility the Hawaii Labor Relations Board will step in to try to press for a resolution.

The board is weighing the merits of a prohibited-practice complaint filed by the union over the state’s decision to impose a contract for teachers. The board, in considering the case, could instruct the union and state to return to the bargaining table.

Joan Husted, former HSTA executive director, said the state and union won’t resolve anything until they get together and talk.

"My concern about the situation is, where is the leadership?" she said. "Who is watching out for the kids and the teachers and Hawaii’s public education system?"