WASHINGTON— Attorney General Alberto Gonzales said yesterday that he has done nothing improper in the firings of eight federal prosecutors in testimony prepared for his appearance before a Senate panel widely viewed as a last chance to save his job.

“I have nothing to hide,” Mr. Gonzales said in a statement released yesterday.

But two Republicans on the Senate Judiciary Committee said Mr. Gonzales has an uphill battle in convincing the public that he can lead the Justice Department.

And Senator Schumer, a Democrat of New York, who is helping run the committee’s investigation, left the door open for more than one hearing if Mr. Gonzales did not fully answer questions. “Fuzzy recollections don’t help us to get to the bottom of what happened,” Mr. Schumer said.

Two days before Mr. Gonzales is to make a showdown appearance before Congress, Senator Specter, a Republican of Pennsylvania, said none of Mr. Gonzales’s public statements so far has convinced him that the department’s ouster of U.S. attorneys was justified.

In an op-ed yesterday in the Washington Post, Mr. Gonzales apologized for the handling of the matter, including a series of misstatements about his exact role that he acknowledged “created confusion.” But Mr. Gonzales maintained that “nothing improper” occurred.

“Those statements are very conclusory,” said Mr. Specter, the top Republican on the Senate Judiciary Committee. “He’s got a steep hill to climb. He’s going to be successful only if he deals with the facts.”

Senator Graham, a Republican of South Carolina, another member of the Judiciary Committee, said Mr. Gonzales has “an uphill struggle to re-establish his credibility with the committee given prior statements.” Still, Mr. Graham said he believed Mr. Gonzales could save his job.

“He needs to explain what he did and why he did it,” Mr. Graham said. “There are three our four different versions of his role in this, and he needs to bring clarity to what he did and why he did it.”

Mr. Gonzales, a former White House counsel who became attorney general in 2005, will testify tomorrow before the committee, in what will likely be a make-or-break appearance for Mr. Gonzales.

Mr. Specter said Mr. Gonzales must explain the firing of the U.S. attorneys case by case — and convince senators they were not done to interfere with or promote ongoing criminal investigations aimed at benefiting Republicans.

If he is unable to do so, Mr. Gonzales should consider reinstating the fired prosecutors, Mr. Specter said.

While a president has a right to replace U.S. attorneys for no reason at all, “you can’t replace them for a bad reason,” he said.

“The no. 1 question is, is he capable of administering the Department of Justice, did he have enough hands on to know what’s happening? Can he explain why these individuals were asked to resign and justify the reasons for doing so?” Mr. Specter said.

In his testimony, Mr. Gonzales claimed a hazy memory, saying he recalled some discussions about at least two possible replacements for vacant U.S. attorney jobs. He also said he recalled “two specific instances” when he was told that then-White House counsel Harriet Miers was seeking updates of the Justice Department’s prosecutor evaluations.

But he indicated he could not definitively say whether he was involved in decisions on which attorneys would be targeted. The few, brief updates on the firings he received from Kyle Sampson, his former chief of staff, “focused primarily on the review process itself,” Mr. Gonzales said.

“During those updates, to my knowledge, I did not make decisions about who should or should not be asked to resign,” Mr. Gonzales said.

Mr. Sampson left the Justice Department over the controversy March 12. He told the Senate Judiciary Committee on March 29 that he remembered discussions with Gonzales “this process of asking certain U.S. attorneys to resign.”

Mr. Gonzales also apologized to the eight fired prosecutors, and their families, for “allowing this matter to become an unfortunate and undignified public spectacle.”

“I am sorry for my missteps that have helped to fuel the controversy,” Mr. Gonzales said.

He added: “In hindsight, I would have handled this differently. … Looking back, it is clear to me that I should have done more personally to ensure that the review process was more rigorous.”

Mr. Schumer said the prepared testimony failed to respond to questions such as whether the firings were politically motivated and Mr. Gonzales’s exact involvement, other than to “point the finger of responsibility at Kyle Sampson.”