The revelations of Mr. Bush's four-year-old order approving domestic surveillance without court warrants has spurred a fiery debate over the balance of power between the White House, Congress and the judiciary.
"I believe in a strong, robust executive authority and I think that the world we live in demands it," Cheney said.
"I would argue that the actions that we've taken there are totally appropriate and consistent with the constitutional authority of the president. ... You know, it's not an accident that we haven't been hit in four years," the vice president said, speaking with reporters on Air Force Two en route from Pakistan to Oman.
Just a year ago, Mr. Bush assured Americans that their civil liberties were being protected in the hunt for terrorists, reports CBS News chief White House correspondent John Roberts.
"A wiretap requires a court order. Nothing has changed, by the way. When we're talking about chasing down terrorists, we're talking about getting a court order before we do so," Mr. Bush said in April of 2004.
The White House said Tuesday that the president was only talking about wiretap provisions under the Patriot Act, reports Roberts.
On Capitol Hill, senators from both parties said the role of Congress cannot be sidelined — even in wartime.
"I think the vice president ought to reread the Constitution," said Sen. Edward Kennedy, D-Mass.
Democrats said they were deeply troubled by the surveillance program, and contended the president had no authority to approve it. "He has no legal basis for spying on Americans without court approval," said Sen. Richard Durbin of Illinois, the No. 2 Democrat in the Senate.
Republicans said Congress must investigate whether Mr. Bush was within the law to allow the super-secret National Security Agency to eavesdrop — without warrants — on international calls and e-mails of Americans and others inside the United States with suspected ties to al Qaeda.
"I believe the Congress — as a coequal branch of government — must immediately and expeditiously review the use of this practice," said Sen. Olympia Snowe, R-Maine.
Snowe joined three other members of the Senate Intelligence Committee, including Nebraska Republican Chuck Hagel, in calling for a joint inquiry by the Senate judiciary and intelligence committees.
The administration defends the program, saying Congress gave Mr. Bush the authority to use "signals intelligence" — wiretaps, for example — to eavesdrop on international calls between U.S. citizens and foreigners when one of them is a suspected al Qaeda member or supporter.