Competition improves the breed, and no breed is more in need of improvement than the U.S. Postal Service. Postmaster General John Potter has proposed ending Saturday delivery because his operation, already a chronic money loser, faces a $7 billion deficit this year and an estimated $238 billion in losses for the current decade. Potter may have the toughest job in town because he faces three immovable objects in his quest to stop the red ink and save a government institution that has been with us since the nation’s earliest days.