Nomination of Sitting Member of Congress to Be Ambassador to Vietnam: Memorandum Opinion to the Counsel of the President [July 26, 1996] [open pdf - 66KB]
"You have asked for our opinion as to whether the Ineligibility Clause of the Constitution, U.S. Const. art. I, § 6, cl. 2, operates to bar the nomination of Representative Douglas ('Pete') Peterson to be Ambassador to the Socialist Republic of Vietnam. We conclude that, in the circumstances of this case, Representative Peterson is not ineligible, provided that the President does not make the determination to create the office of ambassador to that government until after the expiration of the term for which Representative Peterson was elected."
United States. Department of Justice: http://www.justice.gov/