"There comes a point at which, when one is investigating individual Americans...it's necessary to go to a court, have the court weigh and balance the factors, and approve an in-depth investigation," said R. James Woolsey, a Clinton appointee who is now a vice president at the consulting firm Booz Allen Hamilton.
The Bush administration has described the program as narrowly focused on communications in which at least one party is outside the United States or affiliated with Al Qaeda. But Attorney General Alberto Gonzalesat a marathon hearing on Monday that he couldn't assure them that the wiretapping doesn't inadvertently involve nonterrorists.
Speaking at an event here sponsored by the Heritage Foundation, a conservative think tank, Woolsey said that despite those misgivings, he considered himself "somewhere around 75 percent in the administration's camp on this set of issues."
He said he staunchly believes that Article 2 of the U.S. Constitution, which establishes the president's role as commander-in-chief and implicit wartime powers, permits the president to do the kind of "electronic mapping of the battlefield" that the NSA program appears to do.
Also on Thursday, Democratic senators Russ Feingold and Ted Kennedy sent letters to AT&T, Sprint Nextel and Verizon Communications, asking questions about their possible participation in the NSA surveillance program.
The letters ask whether government officials have contacted the telecommunications companies, requesting that they open their networks to eavesdropping. Rep. John Conyers, a Michigan Democrat, also has asked similar questions. (in a report published Monday.)
Woolsey said that because the Constitution already supplies "plenty" such powers, the president need not seek legislative justification for the NSA program. He suggested that one of the administration's--which has involved relying on a congressional resolution passed just after Sept. 11 that authorizes him to use all necessary military force against Al Qaeda and its affiliates--may even create too narrow of a situation.
"I don't believe the president needs to wait for a statute to begin to listen in on conversations between persons affiliated with Hezbollah," he said.
Such a position runs contrary toover the secret wiretapping program's legality from congressional Democrats and Republicans alike since The New York Times first revealed the program's existence in December.
Most recently, Sen. Arlen Specter, a Pennsylvania Republican, saidthat would instruct the secret Foreign Intelligence Surveillance Act, or FISA, Court to determine the constitutionality of the program.
Woolsey said he's not sure what the best forum would be for reviewing governmental requests to drill down on communications involving American citizens, if it chose to go that route. "In order to get into what's going on, it seems to me, the government needs to go through some process that's court-like," he said. "I don't know if it's the FISA Court, or the FISA court remodeled, or another court."
CNET News.com's Declan McCullagh contributed to this report.