Senate Democrats sought a special prosecutor to investigate whether Attorney General Alberto Gonzales lied to lawmakers and they subpoenaed President George W. Bush’s top political aide, Karl Rove, to testify about the firing of U.S. attorneys.

Charges by four Democratic senators that Mr. Gonzales repeatedly lied under oath, plus the latest subpoena, raised the stakes in the congressional fight with Mr. Bush over his refusal to allow aides to testify about the firing of nine prosecutors last year.

The new allegations against Mr. Gonzales came two days after the attorney general appeared before the Senate Judiciary Committee, where he faced expressions of incredulity and disdain from senators in both parties about his answers to questions on Mr. Bush’s surveillance of suspected terrorists.

“The attorney general took an oath to tell the truth, the whole truth and nothing but the truth,” Senator Schumer told reporters yesterday. “Instead, he tells the half-truth, the partial truth, and everything but the truth. And he does it not once, and not twice, but over and over and over again.” In a letter to the Justice Department, the senators said a special counsel should “determine whether Attorney General Gonzales may have misled Congress or perjured himself.” Besides Mr. Schumer, it was signed by Democrats Dianne Feinstein of California, Sheldon Whitehouse of Rhode Island, and Russ Feingold of Wisconsin.

The lawmakers said Mr. Gonzales’s testimony that he never talked to other colleagues about the prosecutor firings after the controversy erupted was contradicted by former aide Monica Goodling. She told Congress in May that she felt “uncomfortable” when Mr. Gonzales raised the subject.

The Democrats also said they found “deeply troubling” Mr. Gonzales’s assertions in 2006 Senate testimony that “there has not been any serious disagreement” in the administration over the interception of suspected terrorists’ international phone calls and emails without court warrants.

The attorney general’s statement was contradicted in congressional testimony earlier this year by the former Deputy Attorney General, James Comey, who said there had been dissent at the highest levels of the Justice Department in March 2004.

The four senators asked the Justice Department to review responses Mr. Gonzales gave two days ago when questioned about Mr. Comey’s testimony that Mr. Gonzales, then the White House counsel, had pressured Attorney General John Ashcroft to extend the intelligence program’s legal authority in March 2004.

Mr. Comey said Mr. Gonzales went to Mr. Ashcroft’s bed in a hospital where he was recovering from emergency gallbladder surgery to persuade the attorney general to reverse a decision not to extend the program.

The director of the FBI, Robert Mueller, yesterday confirmed Mr. Comey’s account, saying that there was disagreement over the National Security Agency’s wiretapping of suspected terrorists.

“I had an understanding the discussion was on an NSA program” that “has been much discussed,” Mr. Mueller, who was outside Mr. Ashcroft’s hospital room, told the House Judiciary Committee.

The senators said they want the special prosecutor to investigate Mr. Gonzales’s assertion that the disagreements by Justice Department officials dealt with another intelligence program, not the terrorism surveillance effort.

Mr. Gonzales said he talked to Mr. Ashcroft not about the surveillance program, but another matter, which had been the subject of a March 10, 2004, White House briefing for congressional leaders. That briefing preceded his hospital visit by a few hours, he said.

Democratic members of Congress who attended the 2004 meeting disputed Mr. Gonzales’s version of events, saying the briefing was about the terrorism surveillance program, not something else. The Democratic senators cited written evidence as well contradicting Mr. Gonzales.

A May 17, 2006, letter to Congress by John Negroponte, then the national intelligence director, included the March 10, 2004, session with lawmakers on a list of briefings congressional leaders received about the surveillance program.

White House and Justice Department officials said Mr. Gonzales stands by his testimony. “The attorney general was speaking consistently,” White House spokesman Tony Snow told reporters yesterday. “The president supports him.”

A Justice Department spokesman, Brian Roehrkasse, said that “confusion is inevitable when complicated classified activities are discussed in a public forum, where the greatest care must be used not to compromise sensitive intelligence operations.”