In a brief question-and-answer session with reporters, the president renewed his pledge to cooperate with the Justice Department investigation to "come to the bottom of this."
"This is a town where a lot of people leak, and I've constantly expressed my displeasure with leaks, particularly of classified information," Mr. Bush said. "I hope we can get this investigation done in a thorough way, as quickly as possible."
Mr. Bush turned the questions on reporters at the end of a Cabinet meeting. "You tell me: how many sources have you had that's leaked information, that you've exposed or had been exposed? Probably none."
"I don't know if we're going to find out the senior administration official," Mr. Bush said. "I don't have any idea. I'd like to. I want to know the truth."
But, Mr. Bush said, "This is a large administration and there's a lot of senior officials."
"I have no idea whether we'll find out who the leaker is, partially because, in all due respect to your profession, you do a very good job of protecting the leakers," Mr. Bush told journalists.
Adding a note of optimism, Mr. Bush said, "But we'll find out."
The president's comments came as officials indicated that lawyers there will spend up to two weeks screening responses turned in by the roughly 2,000 staff members who were asked what — if anything — they knew about the unauthorized disclosure.
The White House sought to collect the last of the documents by a self-imposed deadline of 5 p.m. EDT Tuesday, but acknowledged it probably would not be able to do so.
All White House staffers had until the deadline to certify either that they have produced relevant documents or have no such documents. The order covers materials such as electronic records, telephone logs, correspondence, computer records, notes and calendar entries.
"I expect there may be some that have some extenuating circumstances" such as personal or work-related travel, White House spokesman Scott McClellan said. Nevertheless, White House chief of staff Andrew Card was sending a memo to all staff, reminding them of the deadline.
"We are working hard to make sure the Justice Department has the information that they requested, and this is one step in that process," McClellan said.
The Justice Department is investigating whether someone at the White House, State Department or Pentagon leaked the name of the CIA agent to punish her husband, Joseph Wilson, a former ambassador who criticized the administration's case for war in July.
Wilson had gone to Niger in 2002 to check an allegation that Iraq tried to buy uranium there. He reported finding no evidence. Nonetheless, President Bush made the allegation in his January 2003 State of the Union address. When Wilson wrote in July about his findings in Niger, the White House withdrew the allegation.
Two weeks later, columnist Robert Novak named Wilson's wife as a CIA operative, quoting two administration officials. Those officials may have violated a law against identifying clandestine operatives.
Last week, when the Justice Department announced its probe, White House counsel Alberto Gonzales told presidential aides to preserve all documents and emails relating to Wilson, his wife, Novak and other figures in the case.
McClellan said the White House counsel's office will review the documents before giving them to Justice Department investigators and said that process could take up to two weeks
"I think it's standard practice that in any administration the counsel's office would be the point of contact with the Department of Justice and that they would make sure that the material turned in is responsive to the request," McClellan said. "We'll be turning information in to the Department of Justice over the next couple of weeks."
He said Justice officials had set specific deadlines, but would not specify what they were.
The Los Angeles Times reports the White House's review of the material hints that some claim of executive privilege — which spurred controversy in the Watergate, Iran-Contra and Lewinsky cases — might be made.
Executive privilege is a legal doctrine under which the president and his aides claim the right to keep certain information secret, because disclosing it would hamper the ability of the executive branch to do its job.
A spokeswoman would not say whether the White House intended to make such a claim.
McClellan firmly ruled out any role by three administration officials in the leak: political adviser Karl Rove; Vice President Dick Cheney's chief of staff, I. Lewis "Scooter" Libby; and National Security Council official Elliott Abrams. The spokesman said he had spoken to all three officials about the leak.
The Times reports the Wilson family is considering a civil lawsuit over the affair. Wilson has claimed the move to identify his wife has put her in danger.