WASHINGTON -- A federal judge ordered the Bush administration on Thursday to release documents about its warrantless surveillance program or spell out what it is withholding, a setback to efforts to keep the program under wraps.

At the same time, the Republican chairman of the Senate Intelligence Committee said he had worked out an agreement with the White House to consider legislation and provide more information to Congress on the eavesdropping program. The panel's top Democrat, who has requested a full-scale investigation, immediately objected to what he called an abdication of the committee's responsibilities.

U.S. District Judge Henry Kennedy ruled (.pdf) that a private group, the Electronic Privacy Information Center, will suffer irreparable harm if the documents it has been seeking since December are not processed promptly under the Freedom of Information Act. He gave the Justice Department 20 days to respond to the group's request.

"President Bush has invited meaningful debate about the wireless surveillance program," Kennedy said. "That can only occur if DOJ processes its FOIA requests in a timely fashion and releases the information sought."

Justice Department spokeswoman Tasia Scolinos said the department has been "extremely forthcoming" with information and "will continue to meet its obligations under FOIA."

On Capitol Hill, lawmakers also have been seeking more information about Bush's program that allowed the National Security Agency to eavesdrop -- without court warrants -- on Americans whose international calls and e-mails it believed might be linked to al-Qaida.

After a two-hour, closed-door session, Senate Intelligence chairman Pat Roberts (R-Kansas) said the committee adjourned without voting on whether to open an investigation. Instead, he and the White House confirmed that they had an agreement to give lawmakers more information on the nature of the program. The White House also has committed to make changes to the current law, according to Roberts and White House deputy press secretary Dana Perino.

"I believe that such an investigation at this point ... would be detrimental to this highly classified program and efforts to reach some accommodation with the administration," Roberts said.

Still, he promised to consider the Democratic request for a vote in a March 7 meeting.

Earlier, Bush spokesman Scott McClellan left the impression that any deal with Congress would not allow for significant changes. He said the White House continued to maintain that Bush does not need Congress' approval to authorize the warrantless eavesdropping and that the president would resist any legislation that might compromise the program. "There's kind of a high bar to overcome," McClellan said.

West Virginia Sen. Jay Rockefeller, the Intelligence Committee's top Democrat, said the White House had applied heavy pressure to Republicans to prevent them from conducting thorough oversight. He complained that Roberts didn't even allow a vote on a proposal for a 13-point investigation that would include the program's origin and operation, technical aspects and questions raised by federal judges.

Rockefeller said the Senate cannot consider legislation because lawmakers don't have enough information. "No member of the Senate can cast an informed vote on legislation authorizing or conversely restricting the NSA's warrantless surveillance program, when they fundamentally do not know what they are authorizing or restricting," he said.

It remains unclear what changes in law may look like. Roberts indicated it may be possible "to fix" the 1978 Foreign Intelligence Surveillance Act, or FISA, to authorize the president's program. Perino said the White House considers suggestions put forward by Sen. Mike DeWine (R-Ohio) the starting point, particularly his proposal to create a special subcommittee on Capitol Hill that would regularly review the program.

DeWine's proposal would exempt Bush's program from FISA. That law set up a special court to approve warrants for monitoring inside the United States for national security investigations.

Yet Senate Armed Services Committee chairman John Warner (R-Virginia) left the closed hearing saying he has been working on a different legislative change to FISA. "It seems that's a logical place to start, to upgrade FISA given the extraordinary expanse of technology in the 30 years that have lapsed," he said.

And Senate Judiciary chairman Arlen Specter (R-Pennsylvania) is drafting legislation to require the Foreign Intelligence Surveillance Court to review Bush's program and determine if it is constitutional.

Specter's committee will continue to probe the program's legality at a Feb. 28 hearing. The Justice Department strongly discouraged him from calling former Attorney General John Ashcroft and his deputy, James Comey, to testify about the surveillance program.

Just as Attorney General Alberto Gonzales could not talk about the administration's internal deliberations when he appeared before the committee earlier this month, neither can Ashcroft nor Comey, Assistant Attorney General William Moschella said in a letter to Specter.

"In light of their inability to discuss such confidential information, along with the fact that the attorney general has already provided the executive branch position on the legal authority for the program, we do not believe that Messrs. Ashcroft and Comey would be in a position to provide any new information to the committee," Moschella said.