Senior Bush administration officials spent weeks insisting they would not provide the program's details to more than a select group of eight lawmakers. Briefing the full intelligence committees, Vice President Dick Cheney said in a recent PBS interview, is "not a good way to keep a secret."
But the administration changed direction, offering new operational details to the House Intelligence Committee on Wednesday. A comparable Senate briefing was scheduled for Thursday.
The shift came as Senate Judiciary Committee Chairman Arlen Specter, R-Pa., announced he was drafting legislation that would require the secretive Foreign Intelligence Surveillance Court to review the constitutionality of the administration's monitoring of terror-related international communications when one party to the call is in the United States.
It also came as Rep. Heather Wilson, R-N.M., chairwoman of a House intelligence subcommittee that oversees the NSA, broke with the Bush administration and called for a full review of the NSA's program, along with legislative action to update the 1978 Foreign Intelligence Surveillance Act.
She and others also wanted the full House Intelligence Committee to be briefed on the program's operational details. Although the White House initially promised only information about the legal rationale for surveillance, administration officials broadened the scope Wednesday to include more sensitive details about how the program works.
"I don't think the White House would have made the decision that it did had I not stood up and said, 'You must brief the Intelligence Committee,"' Wilson said at a news conference as Attorney General Alberto Gonzales and Gen. Michael Hayden, the nation's No. 2 intelligence official, briefed the full Intelligence Committee.
When asked what prompted the move to give lawmakers more details, White House spokeswoman Dana Perino said the administration has stated "from the beginning that we will work with members of Congress, and we will continue to do so regarding this vital national security program."
As part of his upcoming bill, Specter said he wants the FISA court to review the program to weigh the nature of the terrorist threat, the program's scope, the number of people being monitored and how the information is being handled.
Since the monitoring program's existence was first revealed in a newspaper report more than 50 days, senior administration officials have argued that Mr. Bush and Cheney were within the law when they chose to brief only the eight lawmakers who lead the House and Senate and their intelligence committees.
After the four-hour House Intelligence Committee session, the panel's chairman, Rep. Peter Hoekstra, R-Mich., said as part of the eight, he still knows more about the program than the rest of the committee. But, he said, "there is very little left to the imagination" of those members who attended Wednesday's meeting.
At least one Democrat left saying he had a better understanding of legal and operational aspects of the anti-terrorist surveillance program. But he said he still had a number of questions.
"It's a different program than I was beginning to let myself believe," said Alabama Rep. Bud Cramer, the senior Democrat on the Intelligence Committee's oversight subcommittee.
Still, Cramer said, some members remain angry and frustrated, and that he didn't understand why the White House waited so long to inform Congress of its actions.
Leaving the House briefing, lawmakers said it covered the Foreign Intelligence Surveillance Act, Justice Department papers outlining legal justifications for the operations, limited details on success stories and some highly sensitive details. None would provide specifics.
Said California Rep. Jane Harman, the panel's top Democrat, "The ice is melting, and we are making progress."
Wilson, Harman and other committee members want to hold hearings on the FISA law to review whether it should be updated. Hoekstra said he was open to hearings, but said such a review has "nothing to do" with the president's program.