White House spokeswoman Dana Perino said the president hoped the US Senate, controlled by Bush's Democratic foes, would confirm Mukasey to replace the scandal-stained Alberto Gonzales before going into recess on October 8.

Gonzales, a close Bush confidant, left the post under a cloud, with Democratic and Republican critics alike charging that he lacked independence from the White House, was incompetent, hid the truth and may be guilty of perjury.

A former top aide to Gonzales revealed earlier this year that she improperly used political criteria in hiring decisions, and Democrats have been probing whether a mass purge of federal prosecutors was tied to political, not legal, considerations.

The nomination could have far-reaching implications for several pitched battles over Bush administration anti-terrorism policies, like warrantless spying on US citizens.

Democratic Majority Leader Harry Reid said Mukasey had "strong professional credentials a reputation for independence" and suggested the former judge "knows how to say no to the president when he oversteps the Constitution."

"But there should be no rush to judgment. The Senate Judiciary Committee must carefully examine Judge Mukasey's views on the complex legal challenges facing the nation," Reid said in a statement.

Democratic Senator Patrick Leahy, chairman of the Judiciary Committee that will take up the nomination before it goes to a vote, promised to review Mukasey's qualifications "a serious and deliberate fashion."

But in a potential hurdle to Mukasey, Leahy also warned that he would take into account White House "cooperation" on existing requests for information on issues like the mass firings and the warrantless surveillance program.

"The next attorney general needs to be someone who can begin the process of restoring the Department of Justice to its proper mission," Leahy, one of Gonzales's fiercest critics, said in a statement.

At the Rose Garden ceremony, which Gonzales did not attend, Mukasey thanked the embattled official for his "support and encouragement" but did not praise his record or his management of the Justice Department.

Mukasey said the department faced "vastly different" challenges from when he served there 35 years ago "but the principles that guide the department remain the same: To pursue justice by enforcing the law with unswerving fidelity to the Constitution."

Mukasey, 66, was appointed a federal district judge in New York under Republican former president Ronald Reagan and retired in 2006, returning to private practice.

He presided over several high-profile terrorism legal cases, including the trial of Omar Abdel-Rahman, the so-called "blind sheikh" who was convicted as the master of a 1993 attack on New York's World Trade Center towers.

Mukasey generally has been supportive of Bush administration policies in the war on terror, although he has at times ruled against the president.

He served as a district judge in the case of Jose Padilla, the US citizen accused by the Bush administration of being an enemy combatant who conspired to kill Americans overseas.

Mukasey upheld the Bush administration's right to detain Padilla indefinitely without charges -- a decision later reversed -- but ruled that he was entitled to a lawyer -- a position the administration argued against.

"That decision hardly makes Mukasey a wild-eyed civil libertarian," said Mark Agrast, a senior fellow with the left-of-center Center for American Progress think tank in Washington.

"But his insistence that the government give Padilla access to counsel was a rare act of principle at a time when few in Congress or the courts were willing to defy the administration," said Agrast.