CHICAGO (CBS) — With 49 elementary schools set to close this summer, and the district facing an additional $412 million in pension costs, the Chicago Teachers Union estimated hundreds — if not thousands — of teachers could be laid off to reduce district spending.

WBBM Newsradio’s Bernie Tafoya reports Chicago Public Schools officials are putting together the district’s budget for next year, and school principals will have to tackle their individual budgets.

The district was already facing an estimated $1 billion deficit before state lawmakers voted down an effort to extend a pension holiday that allowed CPS to contribute less to pensions since 2010. That left the district with a total of $612 million in pension payments next year, rather than $200 million.

CTU Vice President Jesse Sharkey said one factor in possible teacher layoffs would be how much money CPS allocates to schools on a per-pupil basis.

“The district is doing a new budget method, in which they’re going to give money per pupil, and if that per pupil funding is coming in low, there could be as many as thousands of additional layoffs,” Sharkey said. “It’s hard to predict without knowing how the budget numbers are coming in.”

CPS officials have said the school closings were a major part of their plan to cut the deficit, and spokeswoman Becky Carroll told the Chicago Tribune class sizes will not be increased next year, and officials will try to keep cuts “as far away from the classroom as possible.”

She said the board is looking to cut administrative costs first, possibly by moving CPS headquarters out of the Loop to a less-expensive location.