Chicago Teachers Union president Karen Lewis was able to take phone calls before her emergency surgery Wednesday, and a source who is aware of one of those calls described her condition as "serious" and "worrisome."
Friends are concerned, said the source, who asked to remain anonymous.
No further health updates have been released since NBC 5 learned Lewis was being operated on for a "new medical issue" discovered after she became light-headed and experienced "stroke-like symptoms" on Sunday.
Lewis was taken by ambulance to Northwestern Hospital Sunday night after attending a campaign event.
A source insists Lewis did not suffer a stroke, and while it's not clear what kind of emergency surgery she had, NBC 5 was told it was not heart surgery or related to her weight loss surgery.
In March Lewis traveled to Mexico to undergo bariatric surgery, since her health insurance would not pay for the surgery in the United States. Since then, she lost more than 100 pounds.
The 61-year-old union leader has been holding a listening tour across Chicago as she considers a run for mayor. Those close to her campaign said she already has the necessary signatures to get her name on the ballot.
The Chicago Teachers Union plans to hold a news conference Thursday to provide updates on Lewis' health and hospitalization.