PITTSBURGH — West Point graduate and native western Pennsylvanian David McCormick filed paperwork in the Keystone State on Wednesday to run for the open U.S. Senate seat held by retiring Republican Sen. Pat Toomey.

McCormick joins four other Republican contenders — commentator Kathy Barnette, former ambassador to Denmark Carla Sands, heart surgeon Dr. Mehmet Oz and real estate developer Jeff Bartos. The former front-runner, Sean Parnell, quit the race last fall after losing a contentious custody battle in his divorce case.