Michelle A. Rhee butted heads frequently during her three-year tenure as schools chancellor of Washington with the president of the local teachers’ union, George Parker, and eventually a voter backlash over the city’s school reform wars cost both of them their jobs.

Now, in a strange-bedfellows twist, Ms. Rhee has named Mr. Parker as the first senior fellow of Students First, the national group she formed after stepping down as chancellor last fall. She says she hopes Mr. Parker can be a compelling voice for change, especially in speaking to teachers’ union members around the country. He says Ms. Rhee hates teachers’ unions less than most people think.