If the horde of protesters from the Chicago Teachers Union, who raised the humidity in the lobby of City Hall Wednesday morning to an uncomfortable level, could force elected officials to endure the same sticky air until coming up with a fix for underfunded schools, they would.

Chanting and sign waving demonstrators blasted the usual suspects — Mayor Rahm Emanuel, Gov. Bruce Rauner and Chicago Public Schools CEO Forrest Claypool.

Hovering above the muggy mass was a skeleton wearing a cap and gown adorned with a sign, complete with bullet holes, that read: Stop Killing Public Education.

The former Halloween prop is better known to art students at Carl Schurz High School as Charlie Bones — where his likeness is regularly sketched on paper to learn anatomy and proportion.

Schurz teacher Mark Nelson held the skeleton as he explained his position.

“They just don’t get it, they’re not in the trenches with us,” Nelson said of clueless and gridlocked politicians. “It’s like a cadet fresh out of West Point attempting to lead a group of battle hardened troops in the field.”

Union President Karen Lewis, who is vulnerable to illness after successfully battling brain cancer, sat out the protest because of concern over predictions of foul weather, a CTU source said.

Lewis’ second in command, Jesse Sharkey summed up the day by telling fellow protesters: “It’s about demanding funding for our schools. But we haven’t seen the governor or the mayor lift a finger.”

In addition to City Hall, the teachers — who went on summer break this week — gathered at several locations, including the plaza outside the Thompson Center and outside the downtown offices of hedge fund billionaire Ken Griffin, the state’s richest man.

“We need teachers, we need books, we need money Ken Griffin took!” some yelled.

Earlier this month, Claypool said it’s possible that schools in Chicago will not be able to open unless state legislators pass a budget that would help fund CPS. State government has been operating without a budget for nearly a year.

Complicating matters further is the looming threat of a teachers’ strike that could begin when classes resume in the fall. Representatives from CPS and the teachers union continue to meet every Thursday to hammer out a contract that could stave off the potential work stoppage, but a source said Wednesday no progress has been made.

In fact, a step backward was taken Wednesday as Chicago Public Schools announced its intention to file an unfair labor charge against the union over its treatment of teachers who did not participate in a one-day strike on April 1, when CTU members held a protest calling for school funding.

CPS accused the union of “forcibly expelling members who exercised their right to refuse to participate.”

Those who reported to work did so “because their calling is educating their students,” according to a statement issued by Claypool.

“These dedicated professionals should not be expelled for exercising their right to refuse participation in an illegal strike – especially when they came to school to put their students first,” Claypool said in the statement.

The union countered by issuing a statement of their own.

“We find it ironic that Mr. Claypool is now obsessed with defending the ‘rights’ of our members, when CPS has laid off more than 4,000 veteran educators,” the statement read.

“The handful of educators who chose to report to work instead of standing with their courageous colleagues were aware of the consequences of their actions,” according to the statement, which also noted that members who got the boot are eligible to again apply for membership.

Former Gov. Pat Quinn also attended the rally to gather signatures for an effort to create term limits for Chicago’s mayor.

Quinn, who, according to one protest organizer “just showed up,” posed for selfies with fans.

After several people asked Quinn about how he twice dunked a basketball in his youth, he produced from his wallet a folded up photo copy of of a story by Sun-Times columnist Mark Brown that chronicled the athletic feat.

“After this I’m going to dunk on an eight-foot rim,” he joked.

Contributing: Jacob Wittich, Natalie Watts