CHICAGO (CBS) — The Chicago Teachers Union is demanding that the Chicago Public Schools close immediately — including charter schools and contract schools — amid growing concerns about the spread of the coronavirus.

The union also said schools should not serve as polling places on Tuesday.

The teachers’ call for schools to close comes one day after Gov. JB Pritzker announced he is mandating the cancellation or postponement of all events with more than 1,000 people until May 1, and advising all events with more than 250 people also be postponed until May.

Earlier in the day, Mayor Lori Lightfoot said the city is not yet prepared to close schools, noting it would cause “a lot of cascading consequences.”

“If we get to a point where we feel like it’s prudent to close schools, we’re going to do that in a way that mitigates and minimizes the burden that we will be invariably placing on individual households,” she said.

The Archdiocese of Chicago already has announced it is closing all of its Catholic schools starting next week. Many suburban school districts also have started closing schools.

The mayor noted many students at CPS rely on their schools for two or even three meals a day. She also said many CPS parents are hourly workers who would have to lose out on pay to stay home with their kids if schools close, even if those parents and children are healthy.

Lightfoot also said health care workers with kids in CPS would face a difficult choice of whether or not to go to work during a virus outbreak.

“That could mean that we’re taking nurses out of hospitals, doctors out of hospitals,” the mayor said.

The mayor said she, public health officials, and CPS leadership have had regular conversations every day during the coronavirus outbreak to discuss if and when to close public schools.

“Everything that we’ve done and everything that we will do on our citywide coronavirus response is really grounded in the data, and monitored on an hourly basis by our public health officials,” Lightfoot said. “Obviously, we are of course taking every aspect of this very seriously, and particularly the question of whether or not our schools should or should not remain open is something we have frequent conversations about all day long.”

In addition to their demand to close schools, the Chicago Teachers Union is also pushing for state legislation requiring all public and private employees be given 15 paid sick days, to coincide with the recommended two-week quarantine period for anyone who tests positive for COVID-19. Currently, only 12 states have some sort of paid sick time legislation, and Illinois is not one of them.

The union also is demanding the city and CPS establish a plan to ensure all students have access to broadband internet service and computers or mobile devices to participate in remote learning if schools are closed, and for the district to stop using attendance in school performance assessments.