Senate Judiciary Chairman Arlen Specter said Wednesday he remains skeptical about a government surveillance program despite an explanation from Attorney General Alberto Gonzales.

The two met for an hour Sunday to discuss the rationale for the warrantless eavesdropping by the National Security Agency that President Bush approved without obtaining any court orders.

"I would summarize it by saying I have grave doubts about his legal conclusion," Specter, R-Pa., said of a meeting with Gonzales, who was confirmed before Specter's committee early this year. "I'm skeptical, but I'm prepared to listen."

Specter said he expects Gonzales to be the leadoff witness at a hearing on the surveillance, which he said he would like to start next month after confirmation hearings for Supreme Court nominee Samuel Alito.

There likely will be a national debate about whether the president really has the kind of power he's been using, said Specter, a five-term senator and former prosecutor.

"There may be legislation which will come out of it to restrict the president's power," Specter said.

Specter said he would seek a copy of the resignation letter of U.S. District Judge James Robertson, who stepped down from a special court set up to oversee government surveillance. The Washington Post reported that the resignation stemmed from Robertson's concerns over whether the surveillance was legal. Specter said he wants to meet with Robertson, and may ask him to appear before the committee.

President Bush's decision after the Sept. 11, 2001, terrorist attacks to allow domestic eavesdropping without court approval first came to light late last week, and he has defended the decision as a matter of protecting national security.

Specter said the issue isn't one he sought out — that it came up on Friday while he was pushing for passage of the anti-terror Patriot Act.

"When a cannon hits you between the eyes, you take notice and I was immediately asked what I thought about it and I said, 'Well, it's a matter that requires a hearing,"' Specter said.