He serves on a number of boards and advisory committees and is a senior advisor to several entities. He most recently served as CEO of the Comeback America Initiative (CAI), and the Peter G. Peterson Foundation. Previously, Walker served as the seventh comptroller general of the United States and head of the U.S. Government Accountability Office (GAO) for almost ten years (1998–2008).This was one of Walker's three presidential appointments each by different presidents of both major political parties during his 15 years of full-time federal service.