The Chicago Teachers Union is preparing to bring together some 4,000 Chicago Public Schools teachers in a Wednesday rally intended to send a message of solidarity to Mayor Rahm Emanuel amidst ongoing teacher contract negotiations -- and rumors of an imminent strike.

The teachers will be bussed downtown after classes are dismissed to gather at the Auditorium Theatre before hitting the streets just before 6 p.m. and marching to the Board of Education building, NBC Chicago reports. En route, they'll temporarily join forces with Stand Up! Chicago's protest at the CME Group's annual shareholder meeting.

Chicago Teachers Union Vice President Jesse Sharkey told CBS Chicago that no strike vote will be taken at the Wednesday rally, but that such a vote will be taking place "when it’s appropriate" -- a time rumored to be coming soon, before the school year's end.

The Chicago Sun-Times reports that almost 80 percent of CTU members recently rejected the current proposed teacher contract in straw polling, a number that soundly exceeds the minimum support needed for a strike to be called under current law.

At issue for the CTU members are their salaries, the longer school day, resources for their schools, as well as the city's expansion of charter schools while public schools struggle. According to a recent report, CPS is aiming to open 60 new charter schools in the next five years, though the city says that number is as yet only a "projection."

Sharkey told CBS that CPS schools "are going in the wrong direction" politically.

"The board recently announced an 85 percent cut in capital spending, and that happens at the same time that we have schools without playgrounds, that we have schools that are scheduled to meet this summer with no air conditioning, that we have 160 schools without libraries. We feel there is an insufficient plan for that," Sharkey said.

Meanwhile, a forthcoming report by a third-party fact-finder is seeking a compromise between CPS and the teachers. That report is due to be released this summer.

Responding to the union's comments, CPS spokeswoman Becky Carroll said the union "should fully commit to this process and declare no strike authorization votes will be taken before allowing their members to first review the independent fact finder's compromise report," the Chicago Tribune reports.

The union has been debating a strike since the beginning of the school year. Last summer, after the state legislature passed a law cutting into teachers' abilities to negotiate their contracts, modifying tenure and opening the door for a longer school day and year with no guarantees of additional pay, Chicago Teachers Union President Karen Lewis commented that the chances of a strike were "very high."

CPS CEO Jean-Claude Brizard previously commented that talk of a strike amidst ongoing negotiations crossed a line.

Chicago teachers have not gone on strike since 1987.