Updated

The Bush administration's initial proposal to prosecute suspected terrorists drew continued skepticism Wednesday from lawmakers, with a key GOP senator contending that Congress must be given more authority to determine tribunal procedures.

Steven Bradbury, the top legal adviser at the Justice Department, told the Senate Judiciary Committee that the administration's legal proposal was still under review but did not say when it would be finished.

Judiciary Chairman Sen. Arlen Specter, R-Pa., said he would oppose any legislation that would authorize the defense secretary to determine what crimes may be tried by military tribunals — reportedly a provision in an early draft of the administration's proposed bill.

Bradbury confirmed the administration was considering granting the defense secretary such authority but added: "I would not say that the secretary of defense would be creating new crimes from whole cloth, but rather ... recognizing offenses that exist under the laws of war and providing for their prosecution in the military process."

The Supreme Court ruled in June that the Pentagon's military tribunal system, established after the Sept. 2001 terrorist attacks, was not authorized by Congress and violates international treaty obligations on detainee treatment.

Attorney General Alberto Gonzales and Deputy Defense Secretary Gordon England were appearing later before the Senate Armed Services Committee. Chairman John Warner said he expected the administration to outline general recommendations that would help the panel come up with a final legislative proposal by September.

Senate Majority Leader Bill Frist, R-Tenn., said Wednesday he expects a detainee bill to reach the floor in September.

At the Judiciary panel hearing, Specter said handing over control to the administration would invite another challenge by the Supreme Court. "Is there any reason we ought to follow that course that would be risky at best?" Specter said.

"That's certainly an avenue that's open to Congress and one you might judge as appropriate," Bradbury replied.

Military lawyers testifying before the panel agreed with Specter that Congress should make clear who should be tried by military commission. They also said coerced statements should not be admissible in court.

Gen. Richard B. Myers, retired chairman of the Joint Chiefs of Staff, warned the committee that the legislation under consideration would have a significant impact on the war on terrorism.

"I don't think there's a more serious subject being discussed today than this subject," Myers said.

Sen. Lindsey Graham, a member of the Judiciary and Armed Services committees, said administration officials in discussions with him have abandoned their previous position that Congress should simply authorize the existing military tribunal system. The latest proposal under discussion would incorporate aspects of the military's court-martial process, which would afford detainees more rights, Graham said.

Bradbury testified last month that he supports legislation that would back the military's existing tribunal system.

Military lawyers testified Wednesday that a new system should incorporate the Uniform Code of Military Justice because it is well known and internationally respected. Brig. Gen. Kevin Sandkuhler, director of the Marine Corps' Judge Advocate Division, added that he would retain some aspects of the tribunal system.

Graham, R-S.C., Warner, R-Va., and Sen. John McCain, R-Ariz. — who say they support incorporating elements of the court-martial system — have been meeting with administration officials repeatedly in recent days behind closed doors to try to broker a deal.

Democrats have backed the efforts by Graham, McCain and Warner to negotiate the legislation and have supported a system based on the court-martial law.