Mendez is scheduled to announce tomorrow her support for Stewart's challenger, tenant organizer Jumaane Williams.
"It's very aggravating," Williams said. "I don't know if it's disingenuous or just sloppy, but either way, it shouldn't have happened."
Stewart's run for re-election has already been hobbled by revelations that he's a less than ideal landlord, with more than dozen outstanding violations at an apartment building he owns.
"In the final analysis, this election is not about who endorsed or who did not endorse me," Stewart said in a statement. "When special interests and their media buddies start to meddle in the affairs of our community the residents will sit up and take note."