“The CTU is highly insulted,” CTU spokeswoman Stephanie Gadlin told the Chicago Sun-Times.

Late last week, the board told the union it would not offer an optional fourth year of its existing contract that expires June 30, saying the district could not afford the $105 million in raises guaranteed in that deal.

CPS spokesman Bill McCaffrey could not immediately say how much money such a cut would save the district burdened with a $1.1 billion deficit and at least $9 billion in pension obligations.