"When Carter lost in November of 1980, I resigned," said Brady, who later became president of the National Assn. of Former U.S. Attorneys. "Nobody asked me, but that's the tradition of the office. U.S. attorneys serve at the pleasure of the president, and when a new administration comes in, everybody knows you will have a new U.S. attorney."
There have been local exceptions to this rule.
In New York, former Sen. Daniel Patrick Moynihan -- a Democrat who had served in Republican administrations -- persuaded several presidents to allow U.S. attorneys to continue in office after a change of administrations.
In Manhattan, for example, Robert Fiske, a President Ford appointee in 1976, served throughout the Carter administration.
And a Carter appointee, John S. Martin, served during the first years of the Reagan administration.
Many former U.S. attorneys draw a sharp distinction between the political nature of the appointment and the apolitical role of law enforcement.
"The process of selection is political, but once you are there, you can't be political," said Daniel French, who was a Clinton-appointed U.S. attorney in Syracuse, N.Y.
"I don't think there is anything wrong with [former White House Counsel] Harriet Miers saying, 'We want all new people in office.' "
But he said the administration would cross the line if it interfered in a politically sensitive prosecution.
Tom Heffelfinger, a former U.S. attorney from Minnesota who served under Bush -- as well as in the elder Bush's administration -- said a White House move to fire a large number of U.S. attorneys was quite different from replacing the appointees of a previous administration.
"In my opinion, it is not comparable," said Heffelfinger, a Republican who resigned voluntarily from his Justice Department post last year.
"When you have a transition between presidents -- especially presidents of different parties -- a U.S. attorney anticipates that you will be replaced in due course. But the unwritten, No. 1 rule at [the Justice Department] is that once you become a U.S. attorney you have to leave politics at the door," he said.
Democrats in the House and Senate say they intend to press ahead with their investigation to determine whether partisan politics played a role in the dismissal of the eight U.S. attorneys.
For their part, Republican leaders counter that politics is driving the investigation.
Sen. Mel Martinez (R-Fla.), the GOP party chairman, sent out a message Wednesday accusing Democrats of "feigning outrage" over the Justice Department's actions.
"There is no question that U.S. attorneys, like all political appointees, serve at the pleasure of the president," Martinez said. "That was true when Bill Clinton's Justice Department replaced all 93 U.S. attorneys, and it remains true today."
Times staff writer Tom Hamburger contributed to this report.