A reluctant Bush administration finally provided Congress with a broader look at its controversial domestic-spying program Wednesday as frustrated senators said they should have been given oversight “a long time ago.”

The National Security Agency provided new details about the surveillance effort in closed-door briefings one day before the architect of the program was due to appear in a confirmation hearing to head the CIA.

Members of the Senate Select Intelligence Committee said the NSA provided them lots of information about the program, but that they still had lots of unanswered questions.

“It certainly is going to give new meaning to the concept known as a cram course. This is the beginning of something that should have begun years ago,” said Oregon Democratic Sen. Ron Wyden.

Maine Republican Sen. Olympia Snowe said, “It’s an ongoing process. They’re obviously pretty forthcoming, we just have to learn more about it.”

Michigan Democratic Sen. Carl Levin said committee members had “40 or 50” questions about the program that had yet to be answered.

The White House, in an abrupt reversal, agreed on Tuesday to let the full intelligence committee and its counterpart in the House review the program one day before Hayden’s confirmation hearing.

Concerns about the program were expected to dominate Hayden’s hearing because he was the program’s architect as NSA director from 1999 to 2005.

Initiated after the September 11 attacks, the program lets the NSA eavesdrop without a court warrant on international phone calls and e-mails made by people in the United States if one party is suspect to have links with terrorism.

The program has stirred an outcry among civil-rights groups and lawmakers who believe President Bush has overstepped his constitutional authority.

The White House has sought to avoid full committee oversight by limiting briefings to subcommittees from each panel. Initially, the administration shared program details only with the chairmen and vice chairmen of the committees and party leaders in the House and Senate.

Committee Chairman Pat Roberts, a Kansas Republican, said the decision to allow full committee review would ease tensions on the 15-member panel. Democrats have long pushed for full hearings.

“I thought it was very awkward for seven people to be read into the program and eight not,” Roberts said.