The Washington Post reported Walker will become president and chief executive officer of the Peter G. Peterson Foundation, a new Washington-based think tank.
Walker, who led the GAO for about a decade, has been an ardent critic of the costs of the wars in Iraq and Afghanistan, Social Security and Medicare spending, among other things, the newspaper reported.
"Given the fact that significant progress has not been made in improving the living conditions of the Iraqis on a day-to-day basis with regard to things that all citizens care about -- safe streets, clean water, reliable electricity, a variety of other basic things . . . I think you'd have to say it's dysfunctional -- the government is dysfunctional," Walker told the Senate Foreign Relations Committee in September.
Gene Dodaro, the GAO's chief operating officer, will serve as acting comptroller general until a successor for Walker is named.