The Chicago Teachers Union leaders have criticized CPS officials for considering ending the school year 20 days early. View Full Caption DNAinfo/Joe Ward

CHICAGO — Students who rely on getting a little extra help from their teachers after school might be out of luck this week.

Chicago Teachers Union said they have urged their members to clock in and clock out precisely on time Monday through Friday to protest the financial crisis engulfing the Chicago Public Schools that might force officials to end school 20 days early to avoid running out of money.

"We know this will be difficult for many of you, who put your students first, but please consider the powerful message it will send, highlighting to the world how much we do for our students on a voluntary basis," union leaders wrote to teachers.

Teachers might walk out of class May 1 as part of a one-day strike to protest the district's plan to end school 20 days early unless Chicago's schools get more state money. Any walkout would require a vote of the union's membership, which could come April 5.

Chicago Teachers Union staff coordinator Jackson Potter said that possibility has put an "extraordinary amount of pressure" on teachers to scramble to change their lesson plans and make up for the time may be lost.

The plan to cut 13 instructional days from the school year is an "unbelievable attack" on teachers, Potter said.

"We don't want our members to stress themselves out or stress themselves out," Potter said. "We want them to maintain their mental health."

Chicago Public Schools representatives and a spokesman for Mayor Rahm Emanuel did not return an email message about the teachers union's plan.

Teachers work an average of 58 hours per week during the school year, according to a 2012 study conducted by Professor Robert Bruno of the University of Illinois Urbana-Champaign,

That includes nine hours per day at school on average — even though students are in session for no more than seven hours — and two hours at home during the evening, according to the study.

On weekends, teachers spend an average of 3 hours and 45 minutes on work, and 12 days during schools' summer break, according to the study.

Potter said he hoped the action would demonstrate "teachers' extraordinary efforts" on behalf of Chicago's students for school officials, Potter said.

Chicago Public Schools face a $129 million budget deficit — created when Gov. Bruce Rauner vetoed a bill that would have helped the school district pay its pension bill.

That shortfall threatens to force officials to end the school year on June 1 — 20 days early.

Chicago school officials have sued the state, alleging the way Illinois funds schools is discriminatory. Ending the school year early would roll back Emanuel's much-touted efforts to lengthen the school year. In 2012, his push to extend it by 10 days helped trigger a seven-day strike by the Chicago Teachers Union, along with a host of other issues.

"We are seeing the wheels come off" of the mayor's strategy for the schools, Potter said. "He never gave the schools the resources that they needed to make it happen."

The fiscal crisis for Chicago Public Schools began in November, when Rauner blamed Illinois Senate President John Cullerton for violating a compromise made in June that allowed schools to open in September. Part of that deal promised Chicago schools $215 million to help cover its pension obligation in return for statewide "pension reform," a long-held goal of the governor.

But in a December message to legislators, Rauner said he would not sign a school-funding bill because it would amount to a "bailout" for CPS. The governor also wants lawmakers to adopt his agenda, which he said will spur business growth in Illinois, as part of a budget agreement.

Cullerton denied breaking the agreement and said he was willing to continue working on pension reform with the governor.

Rauner and House Speaker Michael Madigan have been locked in a bitter fight over the Illinois budget that has lasted nearly two years.

In January, CPS Chief Executive Forrest Claypool ordered four unpaid furlough days for all CPS employees to save $35 million. The union has objected to that move, officials said.

The next scheduled furlough day for teachers is April 7 and union President Karen Lewis wants it "off the table."

"That would show us some seriousness about them really trying to work with us," she said.

In February, Claypool cut $5 million by canceling professional development events for central office staff and slashed charter school budgets by $15 million by the end of the year, officials said.

Claypool cut another $31 million by freezing a portion of schools' discretionary funds, which can be used to buy textbooks and technology as well as to pay for after-school programs, field trips and hourly staff.

Those cuts leave a CPS deficit of $129 million, officials said.