WASHINGTON (CNN) -- Attorney General-nominee Michael Mukasey made it clear to senators Wednesday he would be independent from the White House and would make legal decisions based "on facts and law, not by interests and motives."
Mukasey, appearing before the Senate Judiciary Committee, said he would resign from office if faced with a presidential order he believed was unconstitutional.
"I would try to talk him [the president] out of it -- or leave," he said.
In his short opening statement, Mukasey said everyone in the Justice Department is "united by shared values and standards."
"I am here in the first instance to tell you, but also to tell the men and women of the Department of Justice, that those are the standards that guided the department when I was privileged to serve 35 years ago, and those are the standards I intend to help them uphold if I am confirmed," Mukasey said.
He said he does not believe the president has legal authority to approve torture techniques for use on terror suspects, something former Attorney General Alberto Gonzales refused to say.
Mukasey disavowed a memo written by former Justice official Jay Bybee that justified certain harsh techniques. "The Bybee memo, to paraphrase a French diplomat, was worse than a sin. It was a mistake. It was unnecessary," he said.
Sen. Patrick Leahy, the Democratic chairman of the committee, has predicted Mukasey, a retired federal judge appointed to the bench by President Reagan, would have no trouble winning Senate confirmation "because we know that we need somebody to clean up the Department of Justice."
Still, Democratic committee staffers predicted tough questioning on a range of hot-button issues -- including no-warrant surveillance and torture policy.
Democratic senators have said they will demand, above all else, assurances the Justice Department will operate independently of White House political operatives.
"Partisan politics will play no part in the bringing of charges or the timing of charges," Mukasey said. He added only Justice Department officials in a "very small group at the top" would be allowed to talk to politicians about cases.
While introducing Mukasey, Sen. Charles Schumer, D-New York, said he has already asked the nominee the key question he wanted answered.
"If confirmed, will you have the courage to look squarely into the eyes of the president of the United States and tell him 'no,' if that is your best legal and ethical judgment?" Schumer said.
"Yes," Mukasey replied.
Under questioning by Leahy about the Bush administration's firing of U.S. attorneys, Mukasey assured him he would not let politics influence prosecutions.
He continued his assurances given in private meetings with senators who were concerned about what they see as civil liberties abuses by the Bush administration.
"Protecting civil liberties," Mukasey said, "and people's confidence that those liberties are protected, is a part of protecting national security, just as is the gathering of intelligence to defend us from those who believe it is their duty to make war on us. We have to succeed at both."
Mukasey said the Guantanamo detention center in Cuba, where hundreds of terror suspects have been held for years, is a "black eye" to the country, but he is not prepared to immediately recommend that it be closed.
The American Civil Liberties Union sought Tuesday to keep pressure on committee Democrats on that issue.
"In particular, we are concerned with his views on the power of the executive branch to authorize indefinite detention of American citizens as enemy combatants without meaningful judicial oversight," the ACLU said. The group also took Mukasey to task for his support of detaining witnesses under the material witness statute.
There was concern earlier in the week over the issue of internal Justice Department documents previously demanded by Congress. It could complicate the proceedings if committee Democrats "decide to pick that fight," a Justice official cautioned Monday.
Sen. Arlen Specter of Pennsylvania, the ranking Republican on the Judiciary committee, has urged the committee not to use the demand for sensitive documents as a precondition for Mukasey's confirmation.
Civil liberties groups have demanded documents relating to torture, interrogation, detention and no-warrant wiretapping.
However, the decisions on turning over sensitive documents ultimately rest with the White House, not with the attorney general. Key Democrats acknowledged as much this week, saying the document access issues would be pursued with the White House "on a parallel track" apart from the Mukasey hearings.
Barring surprises, administration and congressional officials expect Mukasey's testimony to be completed in two days and remaining witnesses to conclude late Thursday or Friday. Leahy has set no date for the committee to vote on the matter, although committee sources said if the hearings go relatively smoothly, a vote is likely by the end of October or early November.
Mukasey retired in 2006 as chief judge of the Southern District of New York, one of the nation's busiest and highest-profile courthouses. He was named to the bench in 1988. E-mail to a friend