WASHINGTON — Attorney General Alberto Gonzales yesterday rejected growing calls for his resignation as scores of newly released documents detailed a two-year campaign by the Justice Department and White House to purge federal prosecutors.

Mr. Gonzales acknowledged his department mishandled the dismissals of eight U.S. attorneys and misled Congress about how they were fired. He said he was ultimately to blame for those “mistakes” but stood by the firings.

“I acknowledge that mistakes were made here,” Mr. Gonzales told reporters at a news briefing after he canceled an out-of-town trip. “I accept that responsibility.” He promised changes “so that the mistakes that occurred in this instance do not occur again in the future.”

He focused on his department’s dealings with Congress concerning the firings rather than the actual dismissals — which Democrats have suggested were politically motivated — and the planning behind them.

“I believe very strongly in our obligation to ensure that when I provide information to the Congress that it’s accurate and that it’s complete. And I am very dismayed that that may not have occurred here,” he said.

Mr. Gonzales also accepted the resignation of his chief of staff, Kyle Sampson. The aide, along with then-White House Counsel Harriet Miers, had begun discussing possible firings of U.S. attorneys in early 2005, according to e-mails released yesterday.

It was the second time in as many weeks that Mr. Gonzales was under fire. Last week, the attorney general and the FBI director, Robert Mueller, admitted the FBI improperly, and at times illegally, used the USA Patriot Act to secretly pry out personal information about Americans in terrorism investigations.

Mr. Gonzales, himself a former White House counsel, has been friends with President Bush for years, going back to when he served as Mr. Bush’s secretary of state in Texas. Mr. Bush retains full confidence in the attorney general, a spokesman Dan Bartlett, said while traveling with Mr. Bush in Mexico.

“He’s a standup guy,” Mr. Bartlett said of Mr. Gonzales.

As for the firings, Mr. Bartlett said White House officials had heard complaints from members of Congress regarding prosecutors and Mr. Bush had raised the subject during an October 2006 meeting with Mr. Gonzales. He described the exchange as “offhand” and said Mr. Bush did not name any specific prosecutors but did identify their states.

“This briefly came up and the president said, ‘I’ve been hearing about this election fraud issue from members of Congress and want to be sure you’re on top of it as well,”‘ Mr. Bartlett said.

Mr. Bartlett said Mr. Gonzales responded, “I know and we’re looking at those issues.”

Democrats clamored for Mr. Gonzales to resign. Republicans also said they were outraged at being misled over the circumstances of the firings. Rep. James Sensenbrenner, a Republican on the Judiciary Committee, said the situation could cause Mr. Gonzales to “die by a thousand cuts.”

For nearly two months, Democrats have accused the Justice Department of playing politics with the prosecutors’ jobs. They suggested some of the U.S. attorneys were fired for either investigating Republicans or failing to pursue cases against Democrats. Several ousted prosecutors have told Congress they were improperly pressured by Republicans on pending cases.

Top Justice officials, including Deputy Attorney General Paul McNulty, have maintained in congressional testimony the dismissals were based on the prosecutors’ performance, not politics. The fired prosecutors headed the U.S. attorneys’ offices in Albuquerque, N.M.; Grand Rapids, Mich.; Las Vegas; Little Rock, Ark.; Phoenix; San Diego, San Francisco, and Seattle.

The e-mails released yesterday disclosed that the firings were considered and discussed for two years by Justice Department and White House officials. The issue first arose in a February 2005 discussion between Mr. Sampson and Ms. Miers, officials said. At the time, Ms. Miers suggested the possibility of firing all 93 U.S. attorneys. Such purges of the political appointees often come at the beginning of a new president’s administration, not midway through.

The e-mails show Mr. Sampson discouraged the across-the-board housecleaning but began a review to weed out prosecutors whom the administration deemed to be performing poorly.

In a September 13, 2006, e-mail message to Ms. Miers, Mr. Sampson listed one prosecutor, Bud Cummins in Little Rock, as “in the process of being pushed out.” Five others — in Arizona, Nevada, Michigan, San Diego and Seattle — were listed as U.S attorneys “we should now consider pushing out.”

Four days later, Ms. Miers responded: “Kyle, thanks for this. I have not forgotten I need to follow up on the info but things have been crazy.”

Mr. Sampson then drew up an elaborate five-step plan to replace the targeted prosecutors with as little political fallout as possible, which he sent in a November 15, 2006, e-mail message to Ms. Miers, deputy White House counsel William Kelley, and Mr. McNulty.

“We’ll stand by for a green light from you,” Mr. Sampson wrote to Ms. Miers and Mr. Kelley. Upon getting their approval, Mr. Sampson wrote, he asked that they “circulate it to Karl’s shop” — which officials confirmed was a reference to Karl Rove, Mr. Bush’s top political adviser and deputy chief of staff.

White House approval came a month later.

“We’re a go for the US Atty plan,” Mr. Kelley wrote in a December 4, 2006, e-mail message to Mr. Sampson and Ms. Miers. “WH leg, political, communications have signed off and acknowledged that we have to be committed to following through once the pressure comes.”

The term “WH leg” refers to the White House office of legislative affairs, which deals with Congress. Copies of dozens of Mr. Sampson’s e-mail messages to various White House and Justice Department officials were released by Congress and the Justice Department.

They also included documents from J. Scott Jennings, the White House deputy political director, who e-mailed Mr. Sampson about the Little Rock prosecutor’s replacement from an address with a “gwb43.com” domain name. That domain is registered to the Republican National Committee, according to a Network Solutions tracking system.

Mr. Cummins told television station KTHV in Little Rock yesterday: “It’s a serious mistake to allow the political people from the White House and other parts of government to get inside the doors of the Department of Justice. There are huge issues at stake there and I’m afraid it’s happened now and the damage is done.”

Democrats on House and Senate judiciary panels said they would subpoena Ms. Miers, Mr. Rove, and other White House and Justice Department officials if necessary to have them testify about the reasons for the firings.

Senator Schumer renewed his call for Mr. Gonzales to resign and was joined by a host of other Democrats, including national party chairman Howard Dean.

“This purge was based purely on politics, to punish prosecutors who were perceived to be too light on Democrats or too tough on Republicans,” Mr. Schumer said. “Attorney General Gonzales has either forgotten the oath he took to uphold the Constitution or just doesn’t understand that his duty to protect the law is greater than his duty to protect the president.”

Among Democrats calling for Mr. Gonzales’s resignation were two presidential candidates, Senators Clinton and Edwards. “The buck should stop somewhere,” Mrs. Clinton said in an interview with ABC’s “Good Morning America” being aired this morning.

Republicans also joined in the criticism.

Senator Ensign of Nevada said the dismissal of the U.S. attorney in Las Vegas was “completely mishandled by the United States attorney general.” And Mr. Sensenbrenner warned that the Justice Department was “going to have to come up with some answers” in explaining the firings.

“If they don’t, they’re going to lose everyone’s confidence,” Mr. Sensenbrenner said. “What I’d like to hear is the truth.”