See also United States v. Mississippi Valley Generating Co., 364 U.S. 520, 552 (1961), where the Supreme Court held that an intermittent consultant to the Bureau of the Budget (a precursor of the Office of Management and Budget) who took no oath of office, had no tenure and received no salary was an officer or agent of the United States within the compass of 18 U.S.C. ?? 434, the statute replace