But across the political spectrum there is concern that the hoarding of information could backfire. Thomas H. Kean, chairman of the Sept. 11 commission and a former Republican governor of New Jersey, said the failure to prevent the 2001 attacks was rooted not in leaks of sensitive information but in the barriers to sharing information between agencies and with the public.

"You'd just be amazed at the kind of information that's classified -- everyday information, things we all know from the newspaper," Mr. Kean said. "We're better off with openness. The best ally we have in protecting ourselves against terrorism is an informed public."

Mr. Kean said he could not legally disclose examples he discovered of unnecessary classification. But others cite cases of what they call secrecy running amok: the Central Intelligence Agency's court fight this year to withhold its budgets from the 1950's and 60's; the Defense Intelligence Agency's deletion of the fact that the Chilean dictator Augusto Pinochet was interested in "fencing, boxing and horseback riding"; and the Justice Department's insistence on blacking out a four-line quotation of a published Supreme Court decision.

Secrecy has long been denounced by liberal watchdog groups like the American Civil Liberties Union. But more conservatives are emerging as skeptics, including Senator John Cornyn, Republican of Texas, whose bill to strengthen the Freedom of Information Act passed the Senate last week. The bill, cosponsored by Senator Patrick J. Leahy, Democrat of Vermont, requires that any legislation creating new exemptions to the Freedom of Information Act explicitly disclose them. It is only part of overhaul efforts proposed by the two.

Mr. Cornyn, a former state attorney general, said he had been trying to persuade his colleagues that freedom of information was not just a concern of the news media. "The people should get the information they need to see if government is doing what they want," he said.