Responding to bipartisan concern about possible abuse of presidential power, the White House laid out a two-pronged argument Monday that President Bush has legal and constitutional authority to order electronic surveillance on domestic targets without court permission.

Despite the secrecy of the ongoing domestic surveillance, the White House had Attorney General Alberto Gonzales and Gen. Michael Hayden, the nation's No. 2 intelligence official, brief reporters:

• The president's constitutional authority as commander in chief covers war-related powers such as ordering the National Security Agency (NSA) to intercept enemy communications wherever they originate, Gonzales said. The 9/11 attacks, he said, showed the enemy was in the USA.

• A resolution Congress passed Sept. 14, 2001, gave Bush power to use "all necessary and appropriate force" to prevent further attacks, language Gonzales said implicitly authorized war-related surveillance.

Lawmakers, including some Republicans, and constitutional scholars said Bush needs to explain why he went around the 1978 Foreign Intelligence Surveillance Act (FISA), a measure imposed after disclosure that the NSA had spied on Vietnam War protesters. The law requires the government to get warrants from a secret federal court before the NSA can conduct domestic surveillance. (Related site: Link to federal law restricting electronic surveillance)

"The Bush administration's argument that post-9/11 actions taken by Congress ... gave the president power to eavesdrop electronically on U.S. persons without even a FISA warrant seems to me a most implausible stretch," Harvard Law Professor Laurence Tribe said. Even a congressional resolution, he said, would "violate the Fourth Amendment ban on unreasonable searches and seizures."

The Supreme Court ruled last year that the congressional resolution implicitly authorized the administration to seize and hold a U.S. citizen as an enemy combatant, an action that Gonzales called more intrusive than electronic surveillance. The detention power was upheld in the case of Louisiana-born Yaser Esam Hamdi, who was captured while fighting in Afghanistan.

Throughout Monday, Bush, lawmakers and administration officials publicly debated an intelligence operation that Gonzales called "probably the most classified program that exists in the United States government."

First reported Thursday night on The New York Times website, the program started shortly after the 9/11 attacks and involved intercepting communications of suspected al-Qaeda affiliates in the USA with people outside the country, Gonzales and Hayden said.

The NSA, which Hayden led at the time, conducted the surveillance because of its sophisticated capabilities to intercept and decode communication.

Bush said key lawmakers had been briefed more than a dozen times on the secret program and had not objected.

Gonzales said the White House rejected the idea of asking Congress to explicitly approve the program because senior lawmakers warned the proposal would probably be defeated.

Getting congressional approval, even in a classified bill, risked exposing the program and thus killing it, Gonzales said.

The NSA was highly selective in picking its targets and limited the time they would be monitored, according to Hayden.

He and Gonzales said it was essential to bypass the legal requirements to obtain secret court warrants for such operations because they had to move quickly to stop terrorist threats.

But they struggled to explain why the administration could not have relied on FISA provisions that allow surveillance to be conducted and a warrant obtained after the fact in emergencies.

Hayden said the effectiveness of the surveillance operations has been eroded by public disclosure, even though the program is continuing. Though logic would suggest al-Qaeda affiliates would be aware of the risk they were being watched and listened to, Hayden suggested some were sloppy in their communication, and the bad habits may vanish with the program's exposure.

Democratic Sens. Carl Levin of Michigan, Russ Feingold of Wisconsin and Jack Reed of Rhode Island, said the domestic spying program should be halted until Congress can hold investigative hearings.

Bush "is the president, not a king," Feingold said.

Sen. Arlen Specter (news, bio, voting record), R-Pa., chairman of the Senate Judiciary Committee, said his panel would hold hearings beginning next month.

Specter and Sen. Patrick Leahy (news, bio, voting record), D-Vt., ranking Democrat on the Judiciary Committee, wrote in separate letters to Supreme Court nominee Samuel Alito that they would be asking him about presidential war powers and a president's ability to order surveillance without court approval.

Lawmakers who got classified briefings over the past four years disagreed on what they were told and whether their objections, if any, would carry any weight.

Former Senate minority leader Tom Daschle, D-S.D., said he had received multiple briefings but their purpose was simply to inform him, not to get his advice or consent.

Daschle also said briefers "omitted key details," including some he called "troublesome - and potentially illegal." He did not elaborate.

Even with an incomplete briefing, Daschle said, he raised objections.

Those who were briefed in the sessions held in Vice President Cheney's office were prohibited from telling anyone about any part of the program, said Sen. Jay Rockefeller, D-W.Va., the vice chairman of the Senate Intelligence Committee.

Rockefeller released a handwritten letter to Cheney dated July 17, 2003, the day he and other House and Senate Intelligence Committee leaders were briefed by then- CIA director George Tenet and Hayden.

"I am neither a technician nor an attorney," Rockefeller wrote. "Given the security restrictions associated with this information and my inability to consult with staff or counsel on my own, I feel unable to fully evaluate, much less endorse these activities."

Rockefeller's comments show Democrats are looking to cover themselves after disclosure of the surveillance, which they knew about, said Rep. Pete Hoekstra, R-Mich., chairman of the House Intelligence Committee.

He and other senior lawmakers were told in detail of the legal arguments behind the surveillance and were invited to air objections, Hoekstra said.

If there had been objections, he said, leaders would have tried to stop the program.

"We are not wallflowers in this process," Hoekstra said.

Commentary: