WASHINGTON -- A report on extensive government collection of Americans' phone data roiled Congress yesterday, with many Republicans rallying to President Bush's defense while one key GOP chairman and many Democrats called for hearings, new restrictions and the possible subpoenaing of telephone executives.

The report in USA Today heaped fuel on an already-simmering debate over privacy rights versus anti-terrorism tactics.

It also threatened to complicate White House efforts to win Senate confirmation of Air Force Gen. Michael Hayden, the former National Security Agency director, as the new CIA director.

"I believe we are on our way to a major constitutional confrontation on Fourth Amendment guarantees of unreasonable search and seizure," said Sen. Dianne Feinstein, D-Calif., a member of the intelligence and judiciary committees. "I think this is also going to present a growing impediment to the confirmation of General Hayden, and that is very regretted."

Several of her colleagues predicted that Gen. Hayden will be confirmed, but activists in both parties said the politics of aggressive surveillance are uncertain and possibly dangerous. Republicans, however, first must address a division in their own ranks.

"The first move by the committee will be to ask the [phone] companies to come in," Senate Judiciary Committee Chairman Arlen Specter, R-Pa., told his colleagues yesterday. "I am prepared to consider subpoenas" if phone executives do not appear voluntarily.

Mr. Specter, who is Congress' most outspoken GOP critic of warrantless wiretaps of Americans, also said he would like to bring Attorney General Alberto Gonzales back to his panel for questions on surveillance "if it would do any good."

Mr. Specter added, "I am determined to get to the bottom of all this."

USA Today disclosed yesterday that the Bush administration has secretly been collecting the telephone records of most American households and businesses without court authority, assembling the records in vast databases and attempting to sift them for clues about terrorist threats.

More than 200 million U.S. telephone accounts and more than a trillion phone calls made since late 2001 are included in the database, but it does not include the contents of the conversations.

Mr. Specter and others have said administration officials including Mr. Gonzales have given insufficient explanations of why anti-terrorism wiretaps cannot be carried out through warrants granted by a secret court.

Mr. Specter appeared to be on a collision course with Majority Leader Bill Frist, R-Tenn., who strongly defended Mr. Bush's surveillance policies. "We'll discuss whether or not hearings are necessary," Mr. Frist told reporters.

But Specter spokesman Bill Reynolds said the chairman ultimately decides which hearings are held.

The USA Today report carried an extra punch on Capitol Hill because it coincided with two related matters: the Hayden confirmation effort and Wednesday night's news that the Justice Department has closed an inquiry into its own lawyers' role in the warrantless wiretaps because investigators could not obtain the security clearances they needed from the administration.

Reps. Jane Harman, D-Calif., and John Conyers, D-Mich. -- the House's top Democrats on the intelligence and judiciary committees, respectively -- filed a bill that would make clear "that any attempt to listen in on Americans or collect telephone or e-mail records must be conducted in accordance with the Foreign Intelligence Surveillance Act of 1978."

The FISA law established the secret court to hear warrant requests for wiretaps of Americans.

Separately, about 50 House Democrats signed a letter to Mr. Bush last night calling on him to appoint a special counsel to investigate NSA eavesdropping practices.

But Senate intelligence committee chairman Pat Roberts, R-Kan., said Congress is adequately briefed, and "calls for further oversight are unnecessary."

Some of his GOP colleagues appeared almost eager to provoke a partisan fight over the issue of wiretaps, with or without warrants.

"To suggest that there's some sort of coverup is not correct, and the motivation of those who would suggest otherwise is obvious," Sen. John Cornyn, R-Texas, said at yesterday's Judiciary Committee hearing, where Ms. Feinstein and others spoke. "We need to be conscious of what's at stake: the security and safety of the American people."

Some liberal activists have cautioned Democrats to move carefully, warning that there are more promising targets, because many Americans appear to back Mr. Bush's claim that warrantless wiretaps are vital in fighting terrorism.

"This issue is a liability for the administration, but given their choices of talking about spying or Iraq or gas prices, they'll take spying, where the American public is split," said Jennifer Palmieri, spokeswoman for the liberal Center for American Progress.

Still, some Democrats from states carried by Mr. Bush in 2000 and 2004 were among the sharpest critics of the phone data collection allegations.

Sen Bill Nelson, D-Fla., who faces re-election this fall, called on the Commerce Committee to launch an investigation into "how and why phone companies voluntarily turned over to the NSA detailed records of calls their customers reportedly made to family members, co-workers, business contacts and others," his office said.

Sen. Ken Salazar, D-Colo., said in a statement, "I have long been concerned about the NSA's domestic spying program, and today's media reports only reinforce that concern. ... The Senate must seek answers from Gen. Hayden."

While Mr. Frist and others were defending Mr. Bush and Gen. Hayden at a news conference just off the Senate floor, Gen. Hayden dashed into a meeting with Majority Whip Mitch McConnell, R-Ky., a few feet away.

Asked about the USA Today story when he emerged, Gen. Hayden replied: "All I would want to say is that everything that NSA does is lawful and very carefully done, and that the appropriate members of the Congress, House and Senate, are briefed on all NSA activities."

White House spokeswoman Dana Perino told reporters, "We're full steam ahead on his nomination."

In the House, Minority Leader Nancy Pelosi, D-Calif., said she asked Speaker Dennis Hastert, R-Ill., "for an immediate congressional review of news reports that the federal government may be collecting information on the phone calls of millions of ordinary Americans."

First Published: May 12, 2006, 4:00 a.m.