Chicago Teachers Union Vice President Jesse Sharkey The Chicago Teachers Union is calling on Mayor Rahm Emanuel and Gov. Bruce Rauner to prevent as many as 5,000 teachers from being laid off later this year.

At a press conference on Monday, CTU Vice President Jesse Sharkey said the layoffs would equate to 140,000-150,000 students losing their teacher.

"Virtually every student will experience chaos as every school in the city will need to be reprogrammed in the middle of the school year," Sharkey told reporters. "The educational experience of our students would be gravely damaged in ways that go beyond those immediate frontline layoffs."

Chicago Public Schools says it will have to send out pink slips if it does not get $480 million from the state to plug a budget hole.

“We agree with CTU that the district faces drastic and unacceptable budget choices. It’s disappointing that the CTU opposed Senate President John Cullerton’s legislation to provide CPS with $500 million in pension funding and relief – which would prevent layoffs no one wants to see,” CPS senior public affairs adviser Emily Bittner said in a statement. “We hope CTU will join us in Springfield in fighting for pension funding equity in order to protect teachers’ jobs and pensions, and the children in our classrooms."

The union says the layoffs would dramatically increase class sizes and cause art and sports programs to be cancelled.

Sharkey did not rule out a possibility of a strike.

On Sept. 14, CTU Vice President Jesse Sharkey told "Chicago Tonight" that contract negotiations "don’t like uncertainty." He added, "There’s a tremendous amount of uncertainty about the whole school year." Hear the full discussion.