Though Mr. Bush made no mention of the subject in his radio address, some of his advisers and national security officials say the White House has decided in the past two weeks to take a hard line with Congressional inquiries into Mr. Bush's secret authorization of wiretaps without warrants on suspects within the United States.

The White House's effort to deflect a Congressional investigation into a secret executive order he issued in 2002 authorizing domestic spying follows a strategy Mr. Bush tried - and ultimately retreated from - in the controversies over why he claimed Saddam Hussein was seeking uranium in Africa and what kind of warnings the White House received about Al Qaeda's ambitions before the Sept. 11 attacks. Mr. Bush's aides and intelligence officials say they plan to refuse to offer more details in public on why they believe the technology of the program made it necessary to bypass the secret court designed to authorize wiretapping efforts inside the United States. They are preparing to dispute vigorously and quite publicly the broader legal critique, offered by some Democrats, the American Civil Liberties Union and some Republicans, that the president acted beyond his authority as commander in chief.

"We're not going to shy away from this debate," Mr. Bush's counselor, Dan Bartlett, said on Friday from Washington.

In interviews over the past week, Mr. Bush's aides said they were convinced that Mr. Bush's decision to admit that he authorized the program - and then to say little about its details - will be enough to keep an increasingly fractious Republican majority in line.