Senate Intelligence Chairman Pat Roberts said he has worked out an agreement with the White House to change U.S. law regarding the National Security Agency's warrantless surveillance program and provide more information about it to Congress.

"We are trying to get some movement, and we have a clear indication of that movement," Roberts, R-Kan., said.

Without offering specifics, Roberts said the agreement with the White House provides "a fix" to the Foreign Intelligence Surveillance Act and offers more briefings to the Senate Intelligence Committee.

The deal comes as the committee was set to have a meeting Thursday about whether to open an investigation into the hotly disputed program. Roberts indicated the deal may eliminate the need for such an inquiry. Democrats have been demanding an investigation but some Republicans don't want to tangle the panel in a testy election-year probe.

"Whether or not an investigation is the right thing to do at this particular time, I am not sure," Roberts told reporters while heading into the meeting.

The White House was not immediately available for comment on Roberts' statement.

Earlier in the day, White House spokesman Scott McClellan hinted at a "good discussion going on" with lawmakers and praised in particular "some good ideas" presented by Sen. Mike DeWine. The Ohio Republican has suggested the FISA law be changed to accommodate the NSA program.

However, McClellan left the impression that any deal 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. "We think there's some good ideas, but we have not seen actual legislation."

Separately, the Justice Department has strongly discouraged the Senate Judiciary Committee from calling former Attorney General John Ashcroft and his deputy to testify about the surveillance program, saying they won't have new information for Congress about it.

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 his former No. 2, James Comey, Assistant Attorney General William Moschella said in a letter to Senate Judiciary Committee Chairman Arlen Specter, R-Pa.

The letter, written Wednesday, was obtained by The Associated Press.

"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 wrote. He was responding to Specter's request that the two men testify this month.

While Moschella indicated their testimony wouldn't be of value, he did not say the committee could not call Ashcroft and Comey to appear.

The Judiciary Committee has been looking into the legality of the National Security Agency's program. In a heated daylong hearing on Feb. 6, four Republicans joined the committee's Democrats in raising questions about whether President Bush went too far in authorizing the wiretapping without court warrants.

Some senators, including Sen. Mike DeWine, R-Ohio, have suggested the law be changed to accommodate the program. Specter wants the secretive Foreign Intelligence Surveillance Court to review the program's constitutionality.

Reports have indicated that Comey and others had reservations about the program in 2004. White House Chief of Staff Andy Card and Gonzales, then the White House counsel, visited Ashcroft about those issues while Ashcroft was in the hospital for gallstone pancreatitis.