"I am confident he would not condone such practices," the Arizona senator told more than 250 students during a town-hall meeting at Coastal Carolina University. "I have been briefed enough to know we are not doing that today anywhere in America's government."
Later, during an appearance in Goose Creek, McCain was asked if there is any indication the government had used the technique in the past.
"I don't know," he replied. "I've never had that information."
Speaking with reporters after addressing about 100 members of a Rotary club, McCain said he is confident Mukasey opposes the practice, which he called a violation of the Geneva Conventions.
Mukasey wrote in response to a question from McCain that he didn't think the president had authority to overrule acts of Congress, McCain said.
Congress has passed laws "which clearly prohibit torture and clearly prohibit waterboarding," McCain said
McCain's support of the embattled nominee came as President Bush defended Mukasey's refusal to say whether he considers waterboarding as illegal torture.
Prospects for Mukasey's confirmation have dimmed because of his refusal to equate waterboarding with torture. Sen. Edward M. Kennedy, D-Mass., said Thursday that he intends to oppose the nomination, arguing that Mukasey's unwillingness to answer definitively on the legality of the interrogation method that simulates drowning increases the chances it could be used against U.S. troops.
Mr. Bush said it was unfair to ask the former judge about interrogation techniques he has not been briefed about. The president also said Mukasey doesn't know if the U.S. uses the technique, but that it wouldn't make sense to tell enemies what the U.S. was doing.
McCain, the decorated Vietnam War veteran who spent 5½ years as a POW, said the U.S. should not engage in torture and there was no need for waterboarding.
"If you inflict enough physical pain on anybody, they will tell you anything you want to know," said McCain, who was starting a three-day campaign trip through South Carolina.