Sen. Mark Kirk, Illinois Republican, talks with staff at the Rehabilitation Institute of Chicago last month. After suffering a stroke in January, the lawmaker recovered at the rehabilitation center. He has been allowed to go home. (Rehabilitation Institute of Chicago via Associated Press)

Sen. Mark Kirk, Illinois Republican, talks with staff at the Rehabilitation Institute of Chicago last month. After suffering a stroke in January, the lawmaker recovered at the rehabilitation center. He has been allowed to go home. (Rehabilitation Institute of Chicago via Associated Press)