CHICAGO – Just three weeks after the resolution of Chicago's first teachers' strike in a quarter-century, Mayor Rahm Emanuel's efforts to improve schools face more upheaval with the resignation of the public school system's CEO.

Emanuel and Jean-Claude Brizard — who announced he was stepping down Thursday after just 17 months in charge of Chicago Public Schools — said the decision was mutual and arose after questions about Brizard's management became a distraction from school reform.

Emanuel said he would introduce Brizard's replacement, Barbara Byrd-Bennett, at a Friday morning news conference. Byrd-Bennett is a former teacher and administrator from Cleveland who had been filling in as Chicago's interim chief education officer and played a far more visible role than Brizard in the teacher contract negotiations.