Alberto Gonzales' former top aide testified Thursday that the attorney general was mistaken when he said he was not involved in the firing of eight U.S. attorneys, adding that the dismissals are "a benign, rather than sinister, story."

Under questioning by Democratic Sen. Charles Schumer of New York, Kyle Sampson said Gonzales was involved in the decision to fire the eight attorneys, attending a meeting on the decision 10 days before it was carried out. He said Gonzales was also wrong when he said other senior Justice Department aides gave Congress inaccurate information because they hadn't been fully briefed about the firings.

"I don't remember if the attorney general ever saw documents. I didn't prepare memos for him on this issue. But we did discuss it as early as — before he became the attorney general, when he was the attorney general designate in January of 2005, I think; and then, from time to time, as the process was, sort of, in a thinking phase through 2005 and 2006. And then I remember discussing it with him as the process sort of came to a conclusion in the fall of 2006," he said.

Sampson said he made recommendations about which attorneys should be fired, but "the decision makers in this case were the attorney general and the president."

The former chief of staff argued that the imbroglio had blown up because of poor explanations, but not poor motivations. He also apologized for the confusion and misunderstanding that accompanied the explanation of the firings to senators. A longtime veteran of the Justice Department, he said he resigned because he let down the attorney general by failing to avoid this messy situation.

"As the attorney general's chief of staff, I could have and should have helped to prevent this. In failing to do so, I let the attorney general and the department down. For that reason, I offered the attorney general my resignation. I was not asked to resign. I simply felt honor-bound to accept my share of blame for this problem and to hold myself accountable," he said.

He added that none of the attorneys were let go because of political manipulations.

"The distinction between political- and performance-related reasons for removing a U.S. attorney is, in my view, largely artificial. A U.S. attorney who is unsuccessful from a political perspective, either because he or she has alienated the leadership of the department in Washington or cannot work constructively with law enforcement or other governmental constituencies in the district, is unsuccessful," Sampson said.

Answering senators' questions, Sampson said he had heard the complaints from Republican Sen. Pete Domenici about fired prosecutor David Iglesias, and the complaints could have registered in his mind while considering the dismissal, but Iglesias' firing, like all the others, was not the result of political maneuvering to prevent or encourage cases being prosecuted.

"Was there any consideration at all of asking Mr. Iglesias to resign because he refused to carry out a prosecution which you thought should have been carried out?" asked Sen. Arlen Specter, R-Pa., the committee's ranking minority member.

"Not to my knowledge," Sampson answered.

He added of the dismissed prosecutor from San Diego that he never made "any connection in my mind between asking Carol Lam to resign and the public corruption case that her office was working on. ... The real problem at that time was her office's prosecution of immigration cases."

The former chief of staff acknowledged that federal prosecutors serve at the president's pleasure and are judged in large part on whether they pursue or resist administration policy. He added that he advised officials not to fire all 93 U.S. attorneys in one fell swoop, but operating on a consensus developed a list of eight to be replaced.

Sampson said "poor judgment, poor word choices and poor communication in preparation for the department's testimony before Congress" made the firings appear to be more than what they are. To make up for those flaws, late Thursday the Justice Department reached an agreement with both House and Senate Judiciary committees to make available six current and two former officials to be interviewed in private by staff and with a transcript to be made and shared with all members.

Sampson's appearance comes about three weeks before Gonzales is scheduled to testify on Capitol Hill amid repeated calls for his resignation from Democrats. Democrats argue the differing accounts of the run-up to the firings is evidence enough of administration manipulation and Gonzales' intent to mislead Congress.

Gonzales said on March 13 that he did not participate in discussions or see any documents about the firings. Documents released last week show he attended a Nov. 27 meeting with senior aides on the topic, where he approved a detailed plan to carry out the dismissals. Gonzales later recanted, saying he had signed off on the plan to fire the prosecutors.

Asked about Gonzales' role in being consulted on attorneys to be fired, White House spokeswoman Dana Perino punted.

"I'm going to have to let the attorney general speak for himself," she said.

Over at the Justice Department, officials close to the attorney general said he had been watching the Sampson hearing "between meetings." Those meetings included seven U.S. attorneys and were intended to help repair relations with the prosecutorial community. The conversation was described as "candid."

The Justice Department acknowledged Wednesday that it gave senators inaccurate information about presidential political adviser Karl Rove's role in trying to secure a U.S. attorney's post in Arkansas for one of his former aides, Tim Griffin.

Justice officials acknowledged that a Feb. 23 letter to four Democratic senators erred in asserting that the department was not aware of any role Rove played in the decision to appoint Griffin to replace U.S. Attorney Bud Cummins in Little Rock, Ark.

Acting Assistant Attorney General Richard Hertling said that certain statements in last month's letter to Democratic lawmakers appeared to be "contradicted by department documents included in our production."

Sampson told lawmakers that at one point he had advocated using a new provision in the Patriot Act to get around Senate confirmation of new federal prosecutors, but Gonzales rejected the suggestion.

"He thought it was a bad idea and he was right," Sampson said. He added that he also "immediately regretted" the decision to suggest that U.S. Attorney Patrick Fitzgerald, who was heading up the Plame Investigation, be removed.

FOX News' Caroline Shively, Trish Turner and Ian McCaleb and The Associated Press contributed to this report.