Attorney General Alberto Gonzales' explanations so far for the Bush administration's failure to obtain warrants for its domestic surveillance program are "strained" and "unrealistic," the Senate Judiciary Committee chairman said Sunday.

Sen. Arlen Specter, whose committee has scheduled hearings Monday on the National Security Agency program, said he believes the administration violated a 1978 law specifically calling for a secretive court to consider and approve such monitoring.

Specter, R-Pa., said he might consider subpoenas for administration documents that would detail its legal justification for the program.

"The president could've taken this there and lay it on the line," Specter said, citing the special court set up under the Foreign Intelligence Surveillance Act of 1978.

"That court has an outstanding record of not leaking. They would be pre-eminently well-qualified to evaluate this program and say it's OK or not OK," Specter told NBC's "Meet the Press."

Under the NSA program put in place after the attacks of Sept. 11, 2001, the government has eavesdropped, without seeking warrants, on international phone calls and e-mails of people within the United States who are deemed to be a terrorism risk.

The administration has defended Bush's decision to bypass the FISA law, saying it is too cumbersome to deal with in a post-Sept. 11 world of heightened security threats. It also said Bush had authority as commander in chief and under a 2001 congressional resolution authorizing force in the fight against terrorism.

"The president's authority to take military action -- including the use of communications intelligence targeted at the enemy -- does not come merely from his constitutional powers. It comes directly from Congress as well," in that post-Sept. 11 resolution, according to Gonzales' prepared testimony for the hearing. The Associated Press on Saturday obtained a copy of his scheduled remarks.

Specter was skeptical.

"I think that contention is very strained and unrealistic. The authorization for use of force never mentions electronic surveillance," Specter said.

In response to written questions submitted to him by Specter before the hearing, Gonzales gives an explanation why the administration bypassed the FISA court: "The delay inherent in the FISA process is incompatible with the narrow purpose of this early warning system."

Specter, however, said that response "was not entirely responsive. ... His answer wasn't really clear." The senator said there is no reason why the administration could not have consulted with the spy court or Congress, who could have changed the law if it was too cumbersome.

But Gen. Michael Hayden, the No. 2 intelligence official in the government, said the FISA process "doesn't give us the speed and agility to do what this program is designed to do."

The program's intent is to "detect and prevent attacks. This is not about long-term surveillance to gather reams of intelligence against a stable and a fixed target," Hayden said on "FOX News Sunday."

Specter's committee has asked the administration to Justice Department documents detailing the legal justification for the NSA program.

Asked about the possibility the committee might subpoena the administration for the material, Specter said he first wanted to hear from Gonzales.

"If we come to it and need it, I'll be open about it," Specter said. He added, "If the necessity arises, I won't be timid."