The Chicago Teachers Union has voted to authorize a strike.
The union announced Monday that 90.6 percent of its membership voted and 95.6 percent approved a strike, clearing the 75 percent approval threshold laid out in a state education law.
CTU's "governing body will meet in a special session on Wednesday, September 28 to determine the next steps, including whether to issue a 10-day strike notice to the Chicago Board of Education," the union said in a statement.
"If that happens, the first possible date for a teachers' strike would be October 11. This would be the third work stoppage by the city's public school educators since Mayor Rahm Emanuel took office in 2011."
The union is still in negotiations with the Chicago Public Schools over a new labor contract. CTU's contract with the school district expired in June 2015.
Benefits and pensions are among the sticking points in negotiations.
CPS has responded to CTU's strike authorization vote.
"A strike can be averted, and CPS will work tirelessly to make sure children's education and progress is not interrupted," the district said in a statement. "CPS teachers have helped propel Chicago students' remarkable academic gains - so even in a difficult financial environment, CPS is offering teachers a raise that was already supported by both the CTU leadership and an independent third party arbitrator."