Atty. Gen. Alberto R. Gonzales, told by President Bush to repair relations with Congress over his handling of the U.S. attorneys affair, instead suffered new and withering criticism from senators of both parties Thursday, including questions about his judgment, candor and fitness to serve.

Testifying before the Senate Judiciary Committee in what one lawmaker called a "reconfirmation hearing," Gonzales apologized for what he described as a flawed process in which a group of young political appointees at the Justice Department led a review that resulted in the firings of eight U.S. attorneys last year.

But his credibility took a fresh hit when he tried to downplay his involvement in the dismissals even as documents and testimony from top aides in recent weeks have shown that he played a central role. His inability to recall basic facts at the hearing -- he answered "I don't recall" more than 50 times -- also often baffled and bewildered lawmakers.

"Your characterization of your participation is significantly, if not totally, at variance with the facts," said Sen. Arlen Specter (R-Pa.), the ranking Republican on the committee.

Gonzales was unable to identify who at the Justice Department and the White House was involved in preparing the final list of prosecutors to be fired.

Several lawmakers said he demonstrated a distressing lack of knowledge about the attorneys' performance before he decided to dismiss them.

Rather, Gonzales testified that he relied on the "consensus recommendation of people that I trusted," admitting that he knew little or nothing about two of seven of the prosecutors who were fired on a single day in December.

He also said he could not remember the date when he finally approved the dismissals.

"Well, how can you be sure you made the decision?" asked Judiciary Committee Chairman Sen. Patrick J. Leahy (D-Vt.).

Lawmakers also challenged Gonzales on how he could make an informed judgment about firing attorneys when his involvement, by his own admission, was limited.

"Since you apparently knew very little about the performance about the replaced United States attorneys, how can you testify that the judgment ought to stand?" asked Sen. Edward M. Kennedy (D-Mass.). "How can you know that none of them were removed for improper reasons?"

Several lawmakers said the reasons Gonzales offered for the dismissals -- including a lack of energy in the case of one fired prosecutor -- sounded contrived. Sen. Lindsey Graham (R-S.C.) called the explanations "a stretch."

"It's clear to me that some of these people just had personality conflicts with people in your office or at the White House and, you know, we made up reasons to fire them," Graham said.

"Sir, I respectfully disagree with that," Gonzales responded. "I really do."

Some of the toughest criticism came from fellow Republicans.

"There are some very serious problems, Mr. Attorney General," said Sen. Jeff Sessions (R-Ala.). "Your ability to lead the Department of Justice is in question."

Sen. Tom Coburn (R.-Okla.) was more blunt. "The best way to put this behind us is your resignation," he told Gonzales, becoming the second Republican member of the Senate to call for the attorney general to quit.

Among the 19 members of the committee, only one -- Sen. Orrin G. Hatch (R-Utah) -- spoke out in defense of Gonzales.

Gonzales sat alone at the witness table in a crowded room that was the site of his confirmation hearing two years ago. Protesters in orange and pink prison garb interrupted the proceedings on several occasions. The words "Arrest Gonzales" were duct-taped to their backs.

The attorney general has been left fighting for his job because he has offered shifting explanations about how closely he was involved in the firings of the prosecutors, who serve as the arms of the Justice Department around the country.

He initially denied at a news conference last month that he was involved in discussions about the purge. He modified his remarks after internal Justice Department documents showed that he had participated in meetings where the prosecutors' fate was discussed.

When Gonzales told the panel that he always prepared for testimony before Congress, Specter shot back: "Do you prepare for your press conferences? And were you prepared when you said you weren't involved in any deliberations?"

At the hearing, Gonzales expressed regret that the dismissals had become an "undignified public spectacle."

"Those eight attorneys deserved better," he told the committee.

He denied, however, that any improper political motives had fueled the dismissals, as Democrats have insinuated, and said that in hindsight he felt the firings were justified.

"It would be improper to remove a U.S. attorney to interfere with or influence a particular prosecution for political gain," he said. "I did not do that. I would never do that."

Gonzales said that he still believed that he could be an effective attorney general, and that his decisions to turn over thousands of department documents to congressional investigators were "not the actions of someone with something to hide."

"I believe that I continue to be effective as the attorney general of the United States," he said. "We've done some great things."

Bush, who said last month that he was troubled that lawmakers said Gonzales had not been straight with them over the firings and instructed him to go to Capitol Hill and patch things up, was "pleased" with Gonzales' testimony, a White House spokeswoman said.

"After hours of testimony in which he answered all of the senators' questions and provided thousands of pages of documents, he again showed that nothing improper occurred," Deputy Press Secretary Dana Perino said. "The attorney general has the full confidence of the president, and he appreciates the work he is doing at the Department of Justice."

The post-hearing assessments were less cheery from some other Republicans.

Late Thursday, Sessions said that the Justice Department might be better served with new leadership. "I think it's going to be difficult for him to be an effective leader," Sessions, a former federal prosecutor, told the Associated Press. "At this point, I think [Gonzales] should be given a chance to think it through and talk to the president about what his future should be."

It is far from certain that Gonzales will be forced to step aside.

The hearing produced no evidence to support the most provocative claim of his critics -- that the firings were orchestrated to affect public corruption cases in a way that would aid Republicans.

And while some senators fumed about the lack of detail that Gonzales offered, Congress is powerless to remove him from office.

Specter, while telling Gonzales that his credibility had been "significantly impaired," said he was not going to call on him to resign. He said the decision was for Gonzales and Bush alone.

Even Democrats, who are driving an intensive investigation into the origins and execution of the firings, conceded they were unable to achieve a knockout blow. "There was no smoking gun, but Gonzales and his cause took 10 to 20 steps back," Sen. Charles E. Schumer (D-N.Y.) told reporters after the hearing.

Schumer, perhaps Gonzales' most outspoken critic, said the hearing pointed up the need to obtain testimony and records from the White House to fully understand how the eight prosecutors were targeted.

The White House has offered to send officials, including political advisor Karl Rove and former White House Counsel Harriet E. Miers, to answer questions about the firings, but only in private and without a transcript. Schumer and other lawmakers have said those terms are unsatisfactory, and are threatening to subpoena the officials.