CHICAGO (WGN) — Chicago Public School students who have been attending in-person learning moved back to remote Wednesday, as the Chicago Teachers Union threaten to go on strike.

On Tuesday afternoon, Chicago Teachers Union (CTU) sent an email to its members that said, in part: “Short of some late-breaking change, *all* CTU members will begin working remotely tomorrow, Wednesday, January 27. And if CPS retaliates against members for exercising their right to a safe workplace, *all* CTU members will stop working on Thursday and set up picket lines at their schools.”

Currently, the only Chicago Public School (CPS) students who have been attending in-person classes are about 19% of eligible pre-kindergarten and cluster program students, who went back a couple of weeks ago.

Kindergarten through eighth grade kids are expected to start in-person classes on Monday, and their teachers were expected to return Jan. 25 — but did not.

CPS then pushed their start date to Wednesday, but that has now changed.

Just one of the sticking points for CTU is that CPS has not agreed to require staff be fully vaccinated against COVID-19 as a prerequsite to appear in-person.

CPS staff became eligible for vaccinations this past Monday. The district has previously said they expect to start giving shots in mid-February.

Chicago Mayor Lori Lightfoot weighed in on the situation on Tuesday, saying, “of course we take your health and safety seriously and we have a plan to ensure you get the vaccine, but we need you to work with us and talk to your leadership. We can’t get there unless we get there together. We need to get a deal done for our children to provide them with safety certainty and stability.”

CTU is now calling for a mediator to broker an agreement on a safe path to returning to schools.