The Senate's No. 3 Democrat said Sunday that Attorney General Alberto Gonzales should resign because he is putting politics above the law.
Sen. Charles Schumer cited the FBI's illegal snooping into people's private lives and the Justice Department's firing of top federal prosecutors.
Schumer said Gonzales repeatedly has shown more allegiance to President George W. Bush than to citizens' legal rights since taking his job in early 2005.
He branded Gonzales, a former White House counsel, as one of the most political attorney generals in recent history.
"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," Schumer said.
"And so this department has been so political that I think for the sake of the nation, Attorney General Gonzales should step down," he said.
Sen. Joe Biden, a member of the Democrat-controlled Judiciary Committee, said Gonzales would be "better off" if he resigned.
"There is very little credibility in the Justice Department right now," Biden said. He cited what he said were abuses of power dating to Gonzales' tenure as White House counsel in which he advocated aggressive interrogations of suspected terrorists that pushed the boundaries of the law.
"I think Gonzales has lost the confidence of the vast majority of the American people," he said. "I think he's lost the confidence of the Congress."
Pennsylvania Sen. Arlen Specter, the top Republican on the Senate Judiciary Committee, said Gonzales' resignation was a "question for the president and the attorney general."
"I do think there have been lots of problems," said Specter, who last week suggested that a Gonzales tenure may have run its course. "Before we come to conclusions, I think we need to know more facts."
Justice spokesman Brian Roehrkasse said the attorney general had made significant strides to protect national security, increase prosecutions of sex offenders and immigration offenses and fight gang violence.
"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," Roehrkasse said.
The lawmakers' comments come after a week in which the Justice Department found itself on the defensive over the dismissal of U.S. attorneys and the FBI's misuse of a type of subpoena known as national security letters.
On Friday, Gonzales and FBI director Robert Mueller acknowledged the FBI had broken the law to secretly pry out personal information about people in the U.S. as part of its pursuit of suspected terrorists and spies.
The admission came after a blistering 126-page report by the Justice Department's inspector general that found agents improperly obtained telephone records and demanded sensitive data. The information was obtained via security letters, which are special warrants issued without judicial approval.
Under criticism by lawmakers, Gonzales also agreed to tighten the law for replacing U.S. attorneys and to let Congress hear from senior department officials with roles in the ousters.
Several U.S. attorneys allege they were unfairly dismissed without reason after they declined to rush corruption investigations into Democrats before last November's congressional election. Gonzales and other officials have denied the charge.
Republican Sen. Lindsey Graham said it is the Bush administration's right to fire U.S. attorneys because they serve at the will of the president. Still, he said, the Justice Department was wrong to attack their reputations.
"I don't believe the attorney general will resign, but this whole episode was unnecessarily poorly handled," Graham said.
Over the weekend, Bush pledged an end to the FBI lapses that caused the illegal snooping but expressed confidence in the response by Mueller and Gonzales. Mueller has accepted responsibility, and both have pledged to fix problems.
Bush said that while the inspector general's report "justly made issue of FBI shortfalls, (it) also made clear that these letters were important to the security of the United States."
On Sunday, Specter and Schumer called the FBI abuses unacceptable. They noted it was Congress that demanded the inspector general review the program even as Justice Department officials were providing assurances the government's surveillance programs were being run responsibly.
In coming hearings by the Judiciary Committee, senators plan to review whether it might be appropriate to scale back some of the government's law enforcement powers in light of the abuses.
"What we found in the Justice Department over and over again is a lack of respect for the rule of law," Schumer said. "There's a view that the executive should be almost without check."
"And that is so wrong," he said. "That's one of the reasons I think we need a change at the top in the Justice Department."
Schumer and Specter were on "Face the Nation" on CBS.