FREMONT -- After a year of contract talks with school district officials that focused on class sizes, salaries and other issues, Fremont teachers on Thursday declared an impasse in negotiations, a union spokesman said.

The matter now goes to the state's Public Employment Relations Board, which can order the two sides to resume bargaining or assign a mediator to help them find an agreement. The teachers' contract expired June 30, 2012.

Teachers have taken 12 unpaid furlough days since 2009, resulting in a total pay cut of $7.2 million for the union's 1,600 members, said teacher Brannin Dorsey, president of the Fremont Unified District Teachers Association.

"Our students are tired of trying to learn in overcrowded classrooms and teachers are fed up with making financial sacrifices with a district that does not respect our dedication," she said.

Dorsey said teachers have scheduled a protest Wednesday at district offices.

District officials say they must be frugal because they project an annual spending deficit of about $6 million until at least 2015.

"This year is particularly difficult because, though the governor is proposing additional state funding, the Legislature has not yet passed the budget," said James Morris, superintendent of schools. "We can't count on additional state funding until the budget is passed."

The Fremont school district has about 33,000 students attending more than 40 schools.

Contact Chris De Benedetti at 510-353-7011. Follow him at Twitter.com/cdebenedetti.