United States Attorney
An United States Attorney is the chief U.S. Department of Justice prosecutor for a judicial district of the United States District Courts. Incumbents are appointed by the President of the United States with the advice and consent of the U.S. Senate. They are supported by Assistant United States Attorneys, who usually do the actual courtroom work.
Some U.S. Attorneys have come from the Assistant Attorney ranks, while others are appointed from outside the Department of Justice. Customarily, the U.S. Attorneys (but not the Assistants) submit resignations when the President changes. Depending on the policies of the particular Administration and the politics of the Attorney, they may be reappointed. Frequently, while they may eventually be replaced, they may be kept on an interim basis if they are involved in significant legal cases.