Walker, a Republican, was appointed to his 15 year term by President Clinton, but spoke out to support "reform" of Social Security during President Bush's effort to privatize Social Security. Walker's new job suggests that he will continue to promote similar goals after leaving the government.
Under Walker's leadership GAO was a cheerleader for former Commissioner Barnhart's hapless Disability Service Improvement (DSI) plan that was ended by the current Commissioner. Indeed, even after DSI had failed miserably, GAO was wondering why it had to be canceled without giving it more of a chance.
GAO in recent years has constantly harped upon the theme of management weakness at Social Security and has consistently downplayed budget as a factor in Social Security's backlog situation.
In leaving, Walker said "As Comptroller General of the United States and head of the GAO, there are real limitations on what I can do and say in connection with key public policy issues, especially issues that directly relate to GAO's client -- the Congress," suggesting that he was leaving because he is unhappy at dealing with a Congress controlled by Democrats.
It seems unlikely that the Senate will confirm anyone nominated by President Bush to replace Walker.