The White House is expected Thursday to unveil the largest overhaul of intelligence powers in a generation, spelling out the responsibilities of each intelligence agency in the wake of several reforms following the 2001 terrorist attacks, according to government officials familiar with the plans.

The revised order states that the new law will be the only law that governs surveillance, in an attempt to quell the concerns of lawmakers who contend that Mr. Bush ignored the law when he authorized a warrantless-spying program after the Sept. 11 attacks.

Some on Capitol Hill were frustrated that the administration kept Congress in the dark on this historic overhaul. "They did not consult Congress at all," said one congressional official.