A former interrogation instructor for the Navy said the words Thursday that congressional Democrats wanted to hear from Attorney General-designate Michael Mukasey: "Waterboarding is torture, period."

"Waterboarding is torture and should be banned," Malcolm Wrightson Nance, a former Navy instructor of prisoner of war and terrorist hostage survival programs, told a House constitutional subcommittee. "I believe that we must reject the use of the waterboard for prisoners and captives and cleanse this stain from our national honor."

Rep. Trent Franks, R-Ariz., said at the panel's hearing that he is against torture but that "sometimes we have to take measures to protect the innocent that we do not like."

"Severe interrogations are sometimes part of doing that," added Franks, the ranking Republican on the panel.

The exchange came as Senate leaders struggled to agree on the timing of a confirmation vote for Mukasey, who has refused to equate waterboarding with illegal torture.

The former retired judge is expected to win confirmation handily, but his nomination has sparked a fresh round of bitter debate about the legality of waterboarding.

The interrogation procedure makes the subject think he's drowning, and has been banned by domestic law and international treaties. Those policies don't cover the CIA's use of the technique, however, and the Bush administration has sidestepped questions about whether it has allowed the agency's employees to use it against terror detainees.

Mukasey's repeated refusal to testify that waterboarding is illegal torture cost him the votes of numerous Democrats in the Senate. But with an assurance that he would enforce any ban on the practice passed by Congress, he won back the votes of two Democrats on the Senate Judiciary Committee, enough for a majority on the panel and a vote by the full chamber.

Both houses of Congress are considering legislation to ban the procedure in all circumstances.

The debate shifted to the House Thursday morning, as the subcommittee, chaired by Rep. Jerrold Nadler, D-N.Y., convened a hearing on how the procedure is carried out and whether it meets the legal definition of torture.

As a former master training specialist in survival programs, Nance said that he underwent waterboarding as part of his training and that he personally led or was involved in using the procedure on hundreds of other trainees at the Navy's Survival, Evasion, Resistance and Escape School.

Nance described the experience as a "slow motion suffocation" that provides enough time for the subject to consider what's happening: "water overpowering your gag reflex, and then feel(ing) your throat open and allow pint after pint of water to involuntarily fill your lungs."

"The victim is drowning," Nance said in materials submitted with his testimony. The intent during training, he added, is to stop the process before death occurs.

Training sessions are where waterboarding belongs, not as part of efforts to gain intelligence information from foreign agents, said a second witness.

Such "coercive" interrogation techniques aren't as effective as those that elicit cooperation, because false information is often elicited under harsher methods, said Col. Steven Kleinman, a senior intelligence officer and military interrogator for the U.S. Air Force Reserves.

"Tragically, many of these same tactics have migrated into the repertoire of interrogators seeking intelligence information," Kleinman said.

Others have said, however, that suspected terrorists have revealed information under harsh interrogation techniques that include waterboarding, such as Khalid Sheik Mohammed, the suspected mastermind of the Sept. 11, 2001, attacks.

A third witness who had agreed to testify said the Pentagon prohibited him from appearing.

Marine Lt. Col. Stuart Couch, appellate judge of the Navy-Marine Corps Court of Criminal Appeals, said he was willing to testify when permitted to do so by the Department of Defense.

In a March 31 Wall Street Journal story, Couch said he had refused to prosecute a suspected terrorist because he believed the evidence had been tainted by torture.