"I believe he should step down, and I don't like saying this," the California senator, a member of the Senate Judiciary committee, said during an interview with Chris Wallace on "Fox News Sunday."
"I think we need to get to the bottom of why these resignations were made, who ordered them, and what the strategy was," she said.
Sen. Trent Lott, R-Miss., said he thought President Bush would be making a "huge mistake" if he agreed to let his top White House advisers testify to Congress on the U.S. attorney firings under oath.
"There is a thing called executive privilege. I do think," Lott, the second-ranking Republican in the Senate, said.
Documents released by the Justice Department on Friday showed Gonzales met with top advisers to discuss the matter 10 days before the politically-botched firings of the eight U.S. attorneys.