Under sometimes strenuous attacks from Senate Democrats, and more gentle criticism from three Republicans, Atty. Gen. Alberto Gonzales Monday defended the Bush administration’s warrantless eavesdropping effort as a vital and legal tool for fighting terrorism, but declined to answer numerous specific questions about the secret surveillance.

“The terrorist surveillance program is lawful in all respects,” Gonzales said, using the administration’s preferred moniker for the effort, which involves intercepting communications between the United States and locations abroad, without prior court approval, in which one party allegedly has unspecified links to terrorism.

“To end the program now would be to afford our enemy dangerous and potentially deadly new room for operation within our own borders,” Gonzales said later during the daylong session before the Senate Judiciary Committee, the first congressional hearing on the controversy.

Despite his insistence about the dramatic stakes involved and the program’s legality, senators from both parties expressed doubts about the Bush administration’s use of the National Security Agency to intercept calls and e-mails on U.S. soil.

“It’s the equilibrium of our constitutional system that’s involved,” said Sen. Arlen Specter, R-Pa., chairman of the panel. “Security is very weighty, but so are civil rights.”

Since the program’s existence was first revealed Dec. 16 by The New York Times, civil libertarians and many Democrats, along with some Republicans and conservative scholars, have charged that the spying violates the1978 Foreign Intelligence Surveillance Act, commonly called FISA. The law regulates eavesdropping against terrorists and foreign agents in the United States and permits warrantless eavesdropping but only if the government obtains court approval within 72 hours of starting the wiretapping.

Thousands of court orders for eavesdropping are issued every year by a special court established under FISA, but the Bush administration has not sought them for the program in question, which began after the Sept. 11, 2001, terrorist attacks.

Gonzales declined to answer numerous questions Monday on the grounds that the answers were classified, including how many U.S. citizens have had their communications intercepted, whether the administration had authorized the opening of U.S. citizens’ mail without warrants or what constitutes terrorist ties.

Gonzales maintains that bypassing the court approval is within Bush’s inherent constitutional power as commander in chief. He also contends Congress allowed for it when lawmakers authorized Bush to use “all necessary and appropriate force” against al-Qaida and those who harbored or assisted it, a vote that came just three days after 9-11 and opened the door to invade Afghanistan.

But Specter and others balked at the claim.

“That just defies logic and plain English,” Specter said, adding that the FISA law contains “a blanket prohibition against any electronic surveillance without a court order.”

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 9/11-resolution so broadly.

And 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.

Graham said he never intended to give Bush “the ability to go around FISA carte blanche” when he voted to invade Afghanistan. He also said Gonzales’ argument that Bush had the necessary constitutional power “could basically neuter the Congress and weaken the courts” if taken to its logical conclusion.