The top Republican on the House's main investigative committee, Rep. Thomas Davis of Virginia, is charging the Justice Department with stonewalling his inquiries about the FBI's assertion that it closed several leak investigations because of a lack of cooperation on the part of other government officials.

In January, Mr. Davis asked the Justice Department about a report in The New York Sun that at least three leak inquiries were shut down after officials at the "victim agency" ignored phone calls and canceled meetings with FBI agents assigned to the probes. The agents said some requests for information were rebuffed for more than a year.

On Friday, the lawmaker, the ranking Republican member of the Oversight and Government Reform Committee, sent a sharply worded letter to Attorney General Gonzales, expressing "aggravation" at the Justice Department's handling of questions about the aborted investigations.

"General Gonzales, it would be an understatement to say I am frustrated and disappointed by your department's response," Mr. Davis wrote. Mr. Davis said he would agree to procedures for a classified briefing, but that the Justice Department replied that "the concern is not classification." Mr. Davis's letter also disclosed that the director of the FBI, Robert Mueller, is conducting an internal review of the bureau's handling of leak cases.

The Republican congressman's complaints about Justice Department intransigence come as the attorney general faces mounting criticism. Yesterday, Senator Schumer urged Mr. Gonzales to resign.

"Attorney General Gonzales is a nice man, but he either doesn't accept or doesn't understand that he is no longer just the president's lawyer, but has a higher obligation to the rule of law and the Constitution, even when the president should not want it to be so," Mr. Schumer said on CBS's "Face the Nation." "This department has been so political that I think, for the sake of the nation, Attorney General Gonzales should step down," said Mr. Schumer, a Democrat of New York who sits on the Judiciary Committee.

In recent days, Mr. Gonzales has faced sustained bipartisan criticism over the administration's dismissal of at least eight U.S. attorneys. The Justice Department claimed that all but one of the departures were sought for performance reasons, but others have seen political overtones to the ousters.

McClatchy Newspapers reported Saturday that the chairman of the Republican Party in New Mexico, Allen Weh, said he complained to the White House twice about the chief federal prosecutor in that state, David Iglesias. Some Republicans were upset that Mr. Iglesias was moving too slowly on a corruption investigation of local Democrats.

Mr. Weh said his first complaint, in 2005, was to an aide to President Bush's top political adviser, Karl Rove. The second conversation was directly with Mr. Rove at a White House event in 2006, the state party official said.

"It wasn't that Iglesias wasn't looking out for Republicans. He just wasn't doing his job, period," Mr. Weh told the newspaper chain. Mr. Iglesias has defended his record and said he resisted political pressure to indict Democrats before the 2006 election.

In an op-ed piece last week, Mr. Gonzales downplayed the flap over the prosecutors as an "overblown personnel matter," though he now seems more contrite about the department's actions.

On Friday, Mr. Gonzales came under fire on a second front, regarding alleged misuse of administrative subpoenas which do not require judicial approval and are known as national security letters. A report by the Justice Department's inspector general found that the FBI sometimes issued the letters without proper authority, obtained data beyond what the law permits, and failed to include more than 8,000 of the information demands in statistics provided to Congress.

Senator Specter of Pennsylvania, the top Republican on the Judiciary Committee, had raised the possibility that Mr. Gonzales might depart his post soon, but appearing on CBS yesterday, Mr. Specter stopped short of calling for the former White House counsel's firing. "I think that's a question for the president and the attorney general, but I do think there have been lots of problems," Mr. Specter said. "Before we come to conclusions we need to know more facts."

However, Mr. Specter said Congress was likely to rein in the FBI's subpoena power. "It has been very badly abused," he said.

Senator Biden, a Democrat of Delaware, said yesterday that America would be "better off" if the attorney general quit. "Gonzales has lost the confidence of the vast majority of Americans," Mr. Biden told CNN's "Late Edition."

A White House spokesman said yesterday that President Bush dismissed the call for Mr. Gonzales's resignation. "The president has confidence in the attorney general," the spokesman, R. Alexander Conant, said. "The attorney general has shown leadership by demanding a new and higher level of accountability of the FBI's use of national security letters in terrorism investigations."

Mr. Conant referred questions about Mr. Rove's alleged involvement in the dismissals of the New Mexico prosecutor to the Justice Department.

In a statement, a spokesman there, Brian Roehrkasse, did not address that issue or comment directly on Mr. Schumer's suggestion that Mr. Gonzales resign.

"The attorney general demonstrated decisive leadership by demanding a new level of accountability to address systematic problems in oversight over some of the FBI's national security tools," Mr. Roehrkasse said, according to the Associated Press.

Another spokesman for the department, Dean Boyd, said Mr. Davis's letter about the leak probes was under review. "As a general matter, we receive outstanding cooperation from victim agencies, including intelligence agencies, during investigations into leaks of classified information," the spokesman said.

The FBI had no immediate response yesterday to a request for comment about the scope of Mr. Mueller's review of leak cases.

The Sun's report that the FBI cited a lack of cooperation when closing investigations into the unauthorized disclosure of classified information was based on records obtained through a Freedom of Information Act lawsuit filed by this reporter.

In a court filing in December, the FBI said 22 investigative files pertaining to leak probes were "missing" with no indication of who had removed them. Late last month, the FBI told the court that 19 of the files have been physically located and that the bureau can account for the three others.