Several members of Congress from both parties have questioned whether the warrantless snooping is legal. That is because it bypasses a special federal court that, by law, must authorize eavesdropping on Americans and because the president provided limited notification to only a few lawmakers.
"It's amazing that people say to me, 'Well, he's just breaking the law.' If I wanted to break the law, why was I briefing Congress?" asked Mr. Bush. One of those who had been informed, Senate Intelligence Committee Chairman Pat Roberts, R-Kan., was sitting behind Mr. Bush during his appearance at Kansas State University.
Mr. Bush's remarks were part of an aggressive administration campaign to defend the four-year-old program as a crucial and legal terror-fighting tool. The White House is trying to sell its side of the story before the Senate Judiciary Committee opens hearings on it in two weeks.
CBS News chief White House correspondent John Roberts reports the White House is keenly aware of the political stakes over privacy issues and is taking every opportunity to say it's mindful of civil liberties — that the program is not a massive
Back in Washington, Gen. Michael Hayden, the former National Security Agency director who is now the government's No. 2 intelligence official, contended the surveillance was narrowly targeted. He acknowledged that the program established a lower legal standard to eavesdrop on terror-related communications than a surveillance law implemented in 1978.
Under the Foreign Intelligence Surveillance Act, government officials had to prove to a secretive intelligence court that there was "probable cause" to believe that a person was tied to terrorism. Mr. Bush's program allows senior NSA officials to approve surveillance when there was "reason to believe" the call may involve al Qaeda and its affiliates.
Hayden maintained that the work was within the law. "The constitutional standard is reasonable. ... I am convinced that we are lawful because what it is we are doing is reasonable," he said at the National Press Club.
Hayden also rejected suggestions that the NSA rank-and-file had problems with the electronic monitoring, saying that the agency's independent watchdog told him Friday that "not a single employee" had registered a concern with that office about the program.
Democrats countered that many important questions remain.
"We can be strong and operate under the rule of law," said Senate Minority Leader Harry Reid, D-Nev. "These are not mutually exclusive principles — they are the principles upon which our nation was founded."
In his remarks, Mr. Bush said that allowing the NSA to monitor the international phone calls and e-mails of Americans with suspected ties to terrorists can hardly be considered "domestic spying."
"It's what I would call a terrorist surveillance program," Mr. Bush said at Kansas State. "If they're making a phone call in the United States, it seems like to me we want to know why."
He said he "had all kinds of lawyers review the process" to ensure it didn't violate civil liberties or the law.
And he insisted that a recent Supreme Court decision backs his contention that he had the authority to order the program through a resolution Congress passed after the 2001 terrorist attacks that lets him use force in the anti-terror fight.
"I'm not a lawyer, but I can tell you what it means: It means Congress gave me the authority to use necessary force to protect the American people, but it didn't prescribe the tactics," Mr. Bush said.
Mr. Bush and Hayden sought to paint the program as vital to national security, trying to turn the scandal into a virtue, Roberts reports. "Had this program been in effect prior to 9/11, it is my professional judgment that we would have detected some of the al Qaeda operatives in the United States," Hayden said.
Attorney General Alberto Gonzales is to deliver a speech on the program Tuesday. And Mr. Bush was going to NSA headquarters outside Washington on Wednesday.
Last week, Gonzales sent congressional leaders a 42-page legal defense of the program. Vice President Dick Cheney defended it in New York last Thursday and briefed congressional leaders at the White House on Friday.
Mr. Bush's top political adviser, Karl Rove, meanwhile, has put Democrats on notice that the White House regards the issue as a political winner for Republicans in this year's congressional elections.
Mr. Bush's nearly two-hour appearance at Kansas State wasn't all serious. Returning to a more casual format that he has used throughout his presidency to sell his policies, he fielded questions that ranged from Iran's geopolitical ambitions to the sort of advice he gets from his wife, Laura.