WASHINGTON — Michael Mukasey, on the witness stand for a second day of hearings on his nomination to be U.S. attorney general, clashed with Senate Democrats over wiretapping of suspected terrorists and what constitutes torture.

The proceedings turned contentious a day after Judge Mukasey received praise and expressions of support from Senate Judiciary Committee members. Yesterday, he faced sharp questions from Democrats over his refusal to condemn some interrogation tactics and his defense of President Bush’s justification for eavesdropping on suspected terrorists without court warrants.

Judge Mukasey refused to say whether he thought simulated drowning, or waterboarding, of terror suspects amounted to torture, only asserting that if it was defined as torture it would be unconstitutional.

“That is a massive hedge,” said Senator Whitehouse, a Democrat of Rhode Island. “I am very disappointed in that answer; I think it is purely semantic.”

While Congress has banned waterboarding, the Bush administration has refused to say whether the Central Intelligence Agency is allowed to use it in questioning suspects. Still, the Judiciary Committee chairman, Senator Leahy, and the panel’s senior Republican, Senator Specter, praised Judge Mukasey at the conclusion of his testimony and said he would win confirmation.

“The real question,” Mr. Leahy said, “is not whether you’ll get confirmed but what kind of attorney general you’ll be.”

Mr. Leahy, a Democrat of Vermont, said he was “a little bit concerned” because Judge Mukasey’s responses seemed less forthcoming than Wednesday, and asked if the apparent change was due to any criticism from the White House.

“I received no criticism,” Judge Mukasey replied, adding that he had dinner with his family after his appearance before the committee.

Judge Mukasey, a 66-year-old retired federal judge from New York, told the panel he didn’t “want to go down the road on interrogation techniques” though he said tactics mentioned by senators like simulated drowning “seem over the line.”

John Hutson, former judge advocate general of the Navy testifying on a panel of legal experts after Judge Mukasey, said in an interview the nominee’s answer on waterboarding was “a missed opportunity to make a strong statement” against abusive interrogation tactics.

“Waterboarding was devised in the Spanish Inquisition,” Mr. Hutson said. “Next to the rack and thumbscrews, it’s the most iconic example of torture.”

Judge Mukasey also rejected suggestions that Mr. Bush’s terrorist spying program was illegal, arguing that the president acted constitutionally to defend the country. He recited Mr. Bush’s assertion that Congress empowered the president to conduct the wiretapping in a 2001 resolution authorizing force against Al Qaeda after the September 11, 2001, attacks.

“Overnight you have gone from being agnostic” about the surveillance program “to holding what is rather a disturbing view,” Senator Feingold, a Democrat of Wisconsin, said. The lawmaker said Judge Mukasey’s position is “the president may violate a statute if he is acting within his” constitutional authority.

“The president is not putting somebody above the law,” Judge Mukasey replied. “The president is putting somebody within the law. The law emphatically includes the Constitution.”

Senator Feinstein, a Democrat of California, disputed Judge Mukasey’s description of the 2001 resolution on Al Qaeda, saying it wasn’t intended to permit wiretapping without court supervision. “It was never discussed. It never came up,” she said.