Stephanie Banchero & Neil King, Jr.

The election of a tough-talking new teachers’ union head here could complicate efforts to turn around the capital’s struggling school system, just as the fragile national effort to overhaul public schools faces a change in educational leaders in this and two other big cities.
Officials who took over in the wake of Michelle Rhee’s departure as chancellor of Washington’s school system said Friday they might refine her signature policies, but promised not to backtrack on closing low-performing schools and evaluating teachers based on student test scores.
But they face a new player in Nathan Saunders, who ousted Washington Teachers’ Union President George Parker in an election last week. Mr. Saunders said he wanted to overhaul the teacher evaluation system Ms. Rhee put into place, and would fight to retain many of the 737 teachers termed low-performing by the school district who could lose their jobs at the end of the school year.