In a round of television appearances, Gonzales provided a more detailed legal rationale for Mr. Bush's decision authorizing the National Security Agency to eavesdrop on international phone calls and e-mails of people within the United States without seeking warrants from courts.
Gonzales said he had begun meeting with members of Congress on the Bush administration's view that Congress' authorization of the use of military force after the Sept. 11, 2001 attacks was ample authorization for the surveillance.
"Our position is that the authorization to use military force which was passed by the Congress shortly after Sept. 11 constitutes that authority," Gonzales said on CBS News' The Early Show.
It was the most detailed legal explanation given by an administration official since the New York Times reported Thursday that since October 2001 Mr. Bush had authorized the NSA to conduct the surveillance.
Gonzales said Congress' action after Sept. 11 essentially "does give permission for the president of the United States to engage in this kind of very limited, targeted electronic surveillance against our enemy."
The domestic spying revelations have outraged members of Congress, with Democrats and Republicans alike calling for an investigation.
The president has, I think, made up a law that we never passed," said Sen. Russell Feingold, D-Wis.
Sen. Arlen Specter, R-Pa., chairman of the Senate Judiciary Committee, said he intends to hold hearings.
"They talk about constitutional authority," Specter said. "There are limits as to what the president can do."
Senate Democratic Leader Harry Reid of Nevada also called for an investigation, and House Democratic leaders asked Speaker Dennis Hastert to create a bipartisan panel to do the same.
President Bush, in a rare live address, said congressional leaders have been apprised of the secret order "more than a dozen times."
First Amendment legal expert Floyd Abrams told CBS News correspondent Randall Pinkston the president is attempting to mitigate his sidestepping of Congress by saying he had informed some lawmakers.
"It is mitigated in the sense that Congress was not completely uninformed," Abrams said. "As a legal matter though, what the president has authorized 30 times may have been illegal 30 times."
"It's been briefed to the Congress over a dozen times, and, in fact, it is a program that is, by every effort we've been able to make, consistent with the statutes and with the law," Vice President Dick Cheney said Sunday in a televised interview to be broadcast Monday evening: "It's the kind of capability if we'd had before 9/11 might have led us to be able to prevent 9/11."
Sen. John McCain, R-Ariz., said there were no objections raised by lawmakers who were told about it.
"That's a legitimate part of the equation," McCain said. But he said President Bush still needs to explain why he chose to ignore the law that requires approval of a special court for domestic wiretaps.