Chicago Mayor Rahm Emanuel is pushing for big changes at Chicago Public Schools next year, including a longer school day, a different calendar and new teacher evaluations.

Chicago Teachers Union officials say teachers at more than 150 schools are ready to go on strike.

Union president Karen Lewis told reporters Thursday that teachers at those schools are testing the “pro-strike sentiment” through informal polls.

“Teachers and paraprofessionals there have voted overwhelmingly, overwhelmingly, to strike should contract negotiations fail and CPS and the mayor does not reverse the hostile climate against us,” Lewis said.

But in to order strike, new Illinois law says the union needs 75 percent of its eligible voting members on board. There are 675 schools in CPS.

Lewis said CPS wants to lock in a five-year contract and is offering teachers a 2 percent raise in the first year, with salaries based on performance in later years.

CPS officials would not comment on the on-going negotiations, but CPS CEO Jean-Claude Brizard said talk of a strike is premature and problematic.

“We shouldn’t be talking about the ‘S-word,’” Brizard said at a news conference Thursday. “Let’s talk about finding a way to work together to improve a system that will benefit nearly a half million children.”

Emanuel reacted strongly to the possibility of teachers walking out of their classrooms.

“Any time anybody’s not focused on their first priority, which is teaching our children, that’s where I get angst,” he said. “Don’t take away from your main mission, your job, what the people of the city of Chicago, the parents, the taxpayers expect of you, which is to teach our children.”

CPS and the union are negotiating a new contract to replace the one that expires on June 30^th. Both parties characterized the negotiations as “cordial,” but said they remain far apart on key issues.

Chicago teachers have not gone out on strike since 1987. Lewis, who said she was a first-year teacher during the last strike, said the climate at CPS is the most hostile she has ever seen.

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