The chairman of the Senate Judiciary Committee said Friday he won't support Attorney General nominee Michael Mukasey, potentially derailing his confirmation over complaints that he hasn't taken a full enough stand against torture.

"No American should need a classified briefing to determine whether waterboarding is torture," said U.S. Sen. Patrick J. Leahy, D-Vt. He planned an afternoon news conference to make the announcement in Burlington.

Sliding support among the panel's Democrats makes it less likely the full Senate will vote to send Mukasey to a Justice Department that has been leaderless for weeks. Four other Democrats on Leahy's panel, which will decide Tuesday whether to approve Mukasey's confirmation, have already said they will not support him.

Once viewed as a sure thing, Mukasey's nomination was threatened during hearings last month in which he repeatedly refused to say whether he considers the simulated drowning interrogation technique known as waterboarding to be a form of torture.

Torture is considered a war crime by the international community and waterboarding has been banned by the U.S. military, but CIA interrogators are believed to have used the technique on terror detainees as recently as a few years ago.

Mukasey has called waterboarding personally "repugnant," but said he did not know enough about how it has been used to define it as torture. He also said he thought it would be irresponsible to discuss it since doing so could make interrogators and other government officials vulnerable to lawsuits.

"I am eager to restore strong leadership and independence to the Department of Justice," said Leahy. "I like Michael Mukasey. I wish that I could support his nomination. But I cannot. America needs to be certain and confident of the bedrock principle-- deeply embedded in our laws and our values -- that no one, not even the president, is above the law."

Mukasey, a retired federal judge, was nominated in September to replace former Attorney General Alberto Gonzales, who resigned after months of questions about his honesty in congressional testimony and whether he allowed the Justice Department to become too entwined in White House politics.

Mukasey needs support from at least one Democrat on the Senate Judiciary Committee for his nomination to be sent to the full Senate for a vote. The four Democrats who sit on the panel and already have said they will oppose him are: Joe Biden of Delaware, Edward M. Kennedy of Massachusetts, Richard Durbin of Illinois and Sheldon Whitehouse of Rhode Island.