Chicago got closer to a possible teachers strike Wednesday afternoon as the Chicago Board of Education and the Chicago Teachers Union rejected the recommendations made by an outside mediator in the ongoing contract negotiations between the union and the financially strapped school district.

The votes to reject the proposal start a 30-day clock ticking. Teachers, who have already authorized a strike, could walk out if no deal is reached by the end of that period. School starts for about one-third of the district’s students on August 13.

Independent “fact finder” Edwin Benn had suggested a 15 to 20  percent raise for teachers in the first year alone. The school district has put the cost of such a raise at $330 million and says it would mean 4,000 teacher layoffs and drastic increases in class sizes.

Board members voted 6 to 0 to reject the offer at a special meeting Wednesday afternoon. Board member Henry Bienen was not present.

The Chicago Teachers Union’s governing body, the House of Delegates, also unanimously rejected  the fact-finder’s report this afternoon. 

The long-awaited report was meant to help teachers and the school district bridge their differences in ongoing contract negotiations. Chicago Public Schools’ opening salary offer included a 2 percent raise in the first year of the contract, while the union wanted a 29 percent pay hike over two years.

The fact finder’s proposal argues that teachers deserve more pay because they’re being asked to work longer school days. It also says the district should continue the decades-old practice of giving teachers yearly raises for more experience and additional pay boosts for more education, known as “step and lane” increases. Chicago Public School officials did not budget for those next year and want to do away with them altogether.

Chicago Public Schools blasted the mediator’s recommended pay raises, saying they are not grounded in “fiscal reality”; the district is planning to completely drain its rainy day fund to help plug a $665 million budget hole. Some have projected the budget deficit for the 2013-14 school year could hit $1 billion, about 20 percent of the district’s operating budget.

CPS officials also say Benn overstepped his authority by weighing in on whether teachers should be paid more for working a longer day. They argue his recommendations should have been limited to cost of living adjustments and general wages.

The fact finding process is new to CPS and CTU. It stems from changes in the state education law championed by Mayor Rahm Emanuel that also allowed the district to unilaterally institute a longer school day and make it harder for the union to strike.