The announcement came after a unanimous vote by more than 700 members of the union's House of Delegates. If the strike occurs in the 400,000-student district, it would be the district's first in 25 years and come at the beginning of the second week of school for most students.
Union President Karen Lewis said both sides are far apart, with teachers worried about issues that include wages, job security and a new evaluation system. If teachers do strike, it would be the district's first in 25 years and occur at the beginning of the second week of school for most students.
"We've done everything that's been asked of us and we continue to be vilified and treated with disrespect," she said, adding that the district's educators are "tired of being bullied, belittled and betrayed."
Lewis says the union, which issued a 10-day strike notice Wednesday, will continue negotiating until an agreement is reached.
Chicago Public Schools CEO Jean-Claude Brizard said if teachers strike, more than 350,000 students will be taken out of their classrooms, and sports for 11,000 student athletes will be suspended. He also noted that free breakfasts won't be available to the hundreds of thousands of students eligible for them.
"That's why we need to take advantage of each of the next 11 days and work until we reach a fair resolution for our teachers that will allow our kids to stay in school where they belong," he said in a statement.
School district officials have announced a contingency plan if there is a strike that includes opening 145 schools for four hours each day, staffed by district employees and volunteers.
In a letter to parents, guardians and caregivers of the district's students, Brizard described the contingency plan as a precaution.
"We have every hope and expectation that we will not have to implement it," he wrote, but added: "We must be prepared."
The last Chicago teachers strike was in 1987 and lasted 19 days. The most recent contract expired in June, when 90 percent of the more than 26,000 union members voted to authorize a strike if a contract was not reached over the summer.
The school district has offered teachers a four-year contract with raises of 2 percent a year, which school board spokeswoman Becky Carroll said would cost $160 million. Lewis has repeatedly said the raise offered by the board is not acceptable.