WASHINGTON (Reuters) - U.S. President George W. Bush defended on Thursday his attorney general nominee Michael Mukasey, who has come under fire from Senate Democrats for refusing to say whether an interrogation technique that simulates drowning is illegal torture.

Attorney General nominee Michael Mukasey litsens to a question on his second day of Senate confirmation hearings on Capitol Hill in Washington October 18, 2007. REUTERS/Jim Young

“I believe the questions he’s been asked are unfair,” Bush said in an Oval Office session with reporters. “He’s been asked to give opinions of a program -- or techniques of a program -- on which he has not been briefed.”

Bush’s effort to win Senate confirmation for Mukasey has run into trouble as Democrats have criticized his refusal to reject the widely denounced interrogation technique known as waterboarding, or simulated drowning, as unlawful torture.

Bush later linked the debate to his declared war on terrorism and suggested that senators were hampering his administration’s ability to pursue suspected terrorists by failing to swiftly approve Mukasey, a retired judge and former prosecutor.

“This is no time for Congress to weaken the Department of Justice by denying it a strong and effective leader,” Bush said in a speech to the Heritage Foundation, a conservative think tank.

Critics have accused the United States of torturing suspects in the war on terrorism, with the CIA reportedly using waterboarding after the September 11 attacks.

Despite Bush’s assurances that he prohibits torture, it is unclear how detainees are treated since he refuses to disclose interrogation techniques.

“There’s an enemy out there. I don’t want them to understand, to be able to adjust one way or the other,” Bush told reporters. “The American people have got to understand the program is important and the techniques used are within the law.”

Bush said of Mukasey, “He doesn’t know whether we use that technique or not.”

‘REPUGNANT TO ME’

Mukasey wrote to the Senate Judiciary Committee’s 10 Democrats on Tuesday that waterboarding, as they described it to him, is “repugnant to me.” But he said he did not know if U.S. interrogation methods violate laws against torture.

Democrats initially praised Mukasey after Bush nominated him last month to succeed Alberto Gonzales, who resigned under pressure. But Mukasey’s statements about waterboarding have raised some doubts about his prospects for confirmation.

The Senate Judiciary Committee is set to vote on Tuesday whether to send Mukasey’s nomination to the full Senate for confirmation.

Some Democrats have already said they plan to oppose Mukasey, including Sen. Edward Kennedy of Massachusetts.

“Waterboarding is torture. Period. Yet Judge Mukasey refuses to say so,” said Kennedy, a senior member of the Senate Judiciary Committee. He said a failure to denounce the “barbaric” practice would put U.S. troops at risk because it would undermine the Geneva Conventions ban on torture.

But Mukasey got some support from two influential Republicans, Sen. John McCain of Arizona and Sen. Lindsey Graham of South Carolina, who said they were satisfied with his statement that waterboarding was repugnant.

“We share Judge Mukasey’s revulsion at the use of waterboarding,” the senators said in a joint statement. They urged Mukasey, after he is confirmed, to make clear publicly that he believes waterboarding is illegal.

McCain, a presidential candidate and former prisoner of war, has been an outspoken critic of waterboarding and other harsh interrogation techniques.

Mukasey’s views on waterboarding are of interest to the lawmakers because as attorney general he would advise the White House and intelligence agencies on what techniques are permissible.

If he declares now that waterboarding is illegal, that could put pressure on him to investigate and prosecute past cases where it was used by the CIA in a secret program of interrogating foreign terrorism suspects, said legislative counsel Christopher Anderson of the American Civil Liberties Union.