WASHINGTON – Senators raised doubts about the legal rationale for the Bush administration’s eavesdropping program Monday, forcing Attorney General Alberto Gonzales to provide a lengthy defense of the operations he called a vital “early warning system” for terrorists.

A handful of Republicans joined Democrats in raising questions about whether President Bush went too far in ordering the National Security Agency’s monitoring operations. The senators were particularly troubled by the administration’s argument that a September 2001 congressional resolution approving use of military force covered the surveillance of domestic communications.

“The president does not have a blank check,” said Judiciary Chairman Arlen Specter, R-Pa., who wants the administration to ask the secretive Foreign Intelligence Surveillance Court to review the program.

“You think you’re right, but there are a lot of people who think you’re wrong,” Specter told Gonzales. “What do you have to lose if you’re right?”

Gonzales didn’t respond to Specter’s proposal directly. “We are continually looking at ways that we can work with the FISA [Foreign Intelligence Service Act] court in being more efficient and more effective,” said the former Texas judge.

Under Bush’s orders, the ultra-secret National Security Agency has been eavesdropping – without warrants – on international communications of people in the United States whose calls and e-mails may be linked to Muslim extremists.

During the daylong committee hearing, Gonzales and the senators reached as far back as eavesdropping ordered by President Washington and delved into court decisions surrounding presidential powers and the 1978 Foreign Intelligence Surveillance Act.

Gonzales repeatedly defended the current program as lawful, reasonable and essential to national security. He said the president’s authority was strongest in a time of war, and he called the monitoring operations an “early warning system designed for the 21st century.” He said no changes in law were needed to accommodate the monitoring.

“To end the program now would be to afford our enemy dangerous and potential deadly new room for operation within our own borders,” he said.

Democrats pressed Gonzales for details about the program and other similar operations, almost all of which he would not provide. They’ve asked Specter to file subpoenas for classified legal opinions on the subject.

“The president and the Justice Department have a constitutional duty to faithfully execute the laws,” said Vermont Sen. Patrick Leahy, the committee’s top Democrat. “Nobody is above the law, not even the president of the United States.”

Leahy asked if the administration has authorized the opening of U.S. citizens’ mail. Throughout the hearing, Gonzales chose his words carefully. “We’re only focused on international communications where one part of the communication is al-Qaida,” he said.

Sen. Dianne Feinstein, D-Calif., asked if the Bush administration had issued “any other secret order or directive” that would be prohibited by law. Gonzales said: “The president has not authorized any conduct that I’m aware of that is in contravention of law.”

Republicans, too, were skeptical. Sen. Mike DeWine, R-Ohio, said Bush’s power – and the country – would be stronger if he came to Congress for statutory authorization.

Sen. Lindsey Graham, R-S.C., said future presidents could be hurt when they seek authorizations to use force because the Bush administration interpreted Congress’ post Sept. 11th-resolution so broadly.

Sen. Sam Brownback, R-Kan., said he wanted to review whether changes were needed in the 1978 intelligence law to permit this type of monitoring.

Gonzales tried to paint eavesdropping as less heavy-handed than firing missiles or holding terrorists in detention. He noted the Supreme Court found it was appropriate to detain an American citizen for fighting alongside al-Qaida. “How can it be that merely listening to al-Qaida phone calls into and out of the country in order to disrupt their plots is not?” Gonzales asked.

He also tried to downplay reports of dissent within the Justice Department. To his knowledge, he said, no one had reservations about the program under discussion. Gonzales however, said he could not tell Sen. Charles Schumer, D-N.Y., whether some department officials felt they needed private legal counsel.

Sen. Richard Durbin, D-Ill., asked Gonzales to help him reconcile public comments from Bush administration officials. Some have said the program is not a “drift net” vacuuming up communications. Yet Homeland Security Secretary Michael Chertoff told one publication that the NSA was culling from “thousands” of phone numbers.

Gonzales said he wanted to study Chertoff’s words. “This is a very narrowly tailored program,” he said.

Democrats repeatedly questioned the truthfulness of Gonzales and Bush, citing statements they’d made about wiretapping before the program became public. In one dustup, Democrats sought – and failed – to have Gonzales sworn in.

Specter said the committee would hold at least two more hearings, which may include Gonzales. Specter has also invited former Attorney General John Ashcroft to testify.