Chicago Teachers Union members are one day closer to their planned Sept. 10 walkout, and on Wednesday they confirmed that that strike date wasn't going anywhere.

CTU President Karen Lewis announced after a union meeting Wednesday that the board is backing away from its controversial merit pay model that would tie fourth-year pay raises to performance, but wouldn't budge on its offer of 2 percent raises every year for four years, the Chicago Sun-Times reports.

Lewis said the district is still making moves away from giving more experienced teachers higher salaries, and so for now, the strike will continue as planned.

According to a release posted on the union's website Thursday, the CTU has filed unfair labor practice charges with the Illinois Educational Labor Relations Board, calling the cancellations of longevity pay increases and sick leave and the implementation of more rigorous evaluation procedures an "unlawful impos[ition of] changes in working conditions] while bargaining was ongoing.

"CPS has imposed these changes because its contract proposals call for the elimination of Step increases and the longevity sick benefit, and imposing onerous teacher evaluation procedures," the union alleges in the release. "CPS is attempting to force these terms on teachers despite the fact that negotiations have not concluded and the CTU has not agreed to them."

The district shot back against the charges with a statement condemning the litigation, according to Fox Chicago:

We are very disappointed that the Chicago Teachers Union has filed unnecessary litigation at a time when our focus should be on negotiations and reaching a fair agreement in order to avoid any disruptions to our kids' school year. It's time to put antics aside and negotiate in good faith on behalf of our students so they can stay in classrooms with their teachers where they belong.

While CPS and the city continue efforts to dissuade the union from striking, this week the district also released its "Children First" contingency plan, which would extend the hours of Park District summer camps and host 4-hour sessions of "positive activities" that include breakfast and lunch at 145 schools.

Should the teachers walk out Monday, it will mark the city's first teachers strike in 25 years.

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