Almost 160 Murrieta teaching positions could be eliminated if the school district doesn't get concessions from its labor unions, school officials said Thursday.

The number would include 108 elementary school teachers and 26 each in the middle and high schools, according to a report from Assistant Superintendent Pat Kelley.

Negotiations are under way with the Murrieta Valley Unified School District's two labor unions, seeking a 7.25 percent across-the-board pay cut.

"We continue to work with our associations," Kelley said. "We are optimistic that we will arrive at ... a resolution to avoid this."

Union leaders did not attend Thursday's meeting.

Kelley expects about 175 teachers to get layoff notices, including some who have been with the district since 2003. That is 18 percent of the district's 973 teachers.

"This is not the direction we want to go," Kelley told the board. "At the same time, it's necessary to do our due diligence."

If the layoffs go though, class sizes will increase in all grades. Kindergarten classes would have 33 students, first- through third-grade classes 32, and fourth- through eighth-grade 35.

In high school, classes in core subjects such as English, math and science, would have 35 students with 40 in elective classes and 60 for physical education.

High school layoffs would hit all subjects, Kelley said.

With layoffs, up to 40 percent of the remaining teachers could find themselves with a new assignment next year, according to Kelley.

"That's very disruptive to our teachers, very disruptive to our school sites, our parents and our students," he said.

The moves come as the district looks to cut $6 million from what was once a $14 million deficit, for the 2010-11 school year, officials said.

That number was whittled down through, among other items, retirements, dismissal of temporary employees and spending $1.7 million in reserve funds.

Teacher layoffs, along with an unspecified number of layoffs among support workers, will fill that $6 million gap, Superintendent Stan Scheer said.

The district's 2009-10 budget anticipated revenue of $147.2 million and expenditures of $157.9 million. Revenue and expenditures for 2010-11 were both projected at $152 million.

Thursday's meeting was for information only. A formal request to authorize the layoffs is scheduled to go before the school board March 8.

If approved, layoff notices will go out the next day to beat the state-imposed March 15 deadline, Scheer said.

No layoff notices were sent out last year, when the district used federal stimulus money and reserve funds to fill its budget gap.

Two years ago, 26 teachers received final layoff notices in May, but all were rehired for the next school year, Kelley said.

Call staff writer Craig Shultz at 951-676-4315, ext. 2625.