In a widening storm over the firings of top federal prosecutors, Attorney General Alberto Gonzales admitted on Tuesday that “mistakes were made” and promised accountability, but pleaded ignorance of the details of the bungled dismissals of eight U.S. attorneys.

Gonzales, a longtime confidant of President Bush, said he wouldn’t step down in the face of heated criticism of his management of the Justice Department.

Gonzales has come under increasingly harsh scrutiny as new information about the politically tinged circumstances of the firings has come to light. And last week, the Justice Department’s inspector general issued a scathing report documenting the FBI’s abuse of surveillance powers under the USA Patriot Act, raising new questions about Gonzales’s ability to lead the nation’s chief federal law enforcement agency.

“I am here because I’ve learned from my mistakes, because I accept responsibility and because I’m committed to doing my job, and that is what I intend to do here on behalf of the American people,” Gonzales said at a news conference in which he defended the firings.

Sen. Charles Schumer, D-N.Y., said Gonzales’ acceptance of responsibility didn’t go far enough and he repeated a call, first made Sunday, for Gonzales to step down.

“His time in office should be over,” Schumer told the Senate. “The U.S. attorney scandal and all the other instances where the attorney general did not protect the rule of law are just too great a weight for the office to bear.”

Even as he acknowledged responsibility for the scandal over the firing of the prosecutors, Gonzales insisted that he did not know the particulars of a plan to dismiss prosecutors that was coordinated by his chief of staff, D. Kyle Sampson, who resigned on Monday.

“I never saw a document,” Gonzales said. “We never had a discussion about where things stood. What I knew was there was an ongoing effort that was led by Mr. Sampson … to ascertain where we could make improvements in U.S. attorney performance throughout the country.”

The Justice Department had characterized the involvement of the White House as minimal, but in recent days, the House Judiciary Committee has released e-mails and other documents that show heavy involvement by former White House Counsel Harriet Miers and other top presidential aides.

In 2005, Miers asked Sampson about the feasibility of firing all 93 U.S. attorneys, a plan that was rejected as too disruptive.

Instead, the White House and Sampson settled on a plan to evaluate and rank U.S. attorneys and fire those deemed to be “underperforming,” according to those documents. Such status included being regarded as insufficiently loyal to President Bush or Gonzales.

One of those fired, David Iglesias of New Mexico, told Congress last week that he felt pressured by two New Mexico Republicans, Sen. Pete Domenici and Rep. Heather Wilson, who both called him about a political corruption investigation involving a prominent Democrat.