"I think the president should replace him," Sununu said in an interview. "I think the attorney general should be fired."
Bush, at a news conference in Mexico, told reporters when asked about the controversy: "Mistakes were made. And I'm frankly not happy about them."
But the president expressed confidence in Gonzales, a longtime friend, and defended the firings. "What Al did and what the Justice Department did was appropriate," he said.
Still, Bush acknowledged the attorney general had a problem to address.
"What was mishandled was the explanation of the cases to the Congress," Bush said. "And Al's got work to do up there."
The developments unfolded as presidential aides labored to protect White House political director Karl Rove and former counsel Harriet E. Miers from congressional subpoenas.
The White House sent Fred Fielding, the presidential counsel, to Capitol Hill to negotiate the terms of any testimony by White House aides in an institutional tug of war reminiscent of the Watergate and the Iran-Contra scandals.
Sununu said the firings of the prosecutors, together with a report Friday by the Justice Department's inspector general criticizing the administration's use of secret national security letters to obtain personal records in terrorism probes, shattered his confidence in Gonzales.
"We need to have a strong, credible attorney general that has the confidence of Congress and the American people," said Sununu, who faces a tough reelection campaign next year. "Alberto Gonzales can't fill that role."
The White House response was curt. "We're disappointed, obviously," said White House press secretary Tony Snow.
Sununu has long been a critic of what he has said were the White House's disregard for civil liberties in its war on terrorism. He played a large part in forcing the administration to accept new curbs on its power during the reauthorization of the PATRIOT Act last year.
Some of the dismissed prosecutors complained at hearings last week that lawmakers tried to influence political corruption investigations. Several also said there had been Justice Department attempts to intimidate them.
