Gonzales said he reached an agreement with Sen. Arlen Specter, R-Pa., chairman of the Senate Judiciary Committee, to answer questions about the legal basis for the National Security Agency's warrantless eavesdropping on telephone conversations between suspected terrorists and people in the United States.
"We believe the legal authorities are there," Gonzales said at a news conference at the Justice Department. "The president acted consistent with his legal authority in a manner that he thought was necessary and appropriate to protect the country against this new kind of threat."
The attorney general said he will not discuss operational aspects of the program at the hearing, which is expected to occur next month. Specter said Sunday that he had asked Gonzales to testify publicly.
The attorney general was White House counsel when Mr. Bush initiated the program, but he refused to say Friday what role he played in developing the legal case to support it.
Administration officials also have not said how many people have been targeted for eavesdropping.
Democrats and Republicans in Congress, legal scholars and analysts at the nonpartisan Congressional Research Service have questioned whether the NSA program is within the law.
The program's existence was first reported in The New York Times last month. Soon after, Mr. Bush acknowledged he had authorized the NSA eavesdropping in the months after the attacks of Sept. 11, 2001. He said his legal authority rested on his constitutional powers and the congressional resolution authorizing the use of force following Sept. 11.
The NSA program bypassed the special court Congress established in 1978 to approve or reject secret surveillance or searches of foreigners and U.S. citizens suspected of terrorism or espionage.
Gonzales previously has defended the program, saying last month that the NSA did not seek warrants from the secretive Federal Intelligence Surveillance Act court because "we don't have the speed and the agility that we need in all circumstances to deal with this new kind of enemy."