The homeless, knife-wielding man shot outside the White House Tuesday was charged today with assaulting a federal officer. The single charge carries a penalty of up to 10 years in prison. The accused, Marcelino Corniel, remained hospitalized in critical condition today in a nearby hospital. Corniel was shot twice by U.S. Park Police officers after charging across Pennsylvania Ave. brandishing a knife. Police defended the shooting, pointing out that Corniel refused repeated requests to surrender the weapon, which was strapped to his arm.