Chicago Teachers Union President Karen Lewis is speaking for the first time since suffering a stroke in October.
Lewis has recorded a campaign radio ad for Brandon Johnson, who is running in the Democratic primary against Cook County Commissioner Richard Boykin.
Johnson is a Chicago teacher who has criticized Boykin for having Republican values.
Lewis has not made any public appearances, but has responded to texts as she recovers from this latest setback.
The CTU president was first diagnosed with a brain tumor in 2015 as she was considering a run for mayor. Recently she's taken a medical leave to work on stroke rehabilitation.
The new radio ad will begin airing this weekend.
NBC Chicago reached out to Boykin for comment on the ad, but he said he has not yet heard it.