WASHINGTON - As Congress prepares to consider extending crucial provisions of the USA Patriot Act, civil liberties groups and some Democratic lawmakers are gearing up to press for sweeping changes to surveillance laws.
Both the House and the Senate are set to hold their first committee hearings this week on whether to reauthorize three sections of the Patriot Act that expire at the end of this year. The provisions expanded the power of the F.B.I. to seize records and to eavesdrop on phone calls in the course of a counterterrorism investigation.
Laying down a marker ahead of those hearings, a group of senators who support greater privacy protections filed a bill on Thursday that would impose new safeguards on the Patriot Act while tightening restrictions on other surveillance policies. The measure is co-sponsored by nine Democrats and an independent.
Days before, the Obama administration called on Congress to reauthorize the three expiring Patriot Act provisions in a letter from Ronald Weich, assistant attorney general for legislative affairs. At the same time, he expressed a cautious open mind about imposing new surveillance restrictions as part of the legislative package.
"We are aware that members of Congress may propose modifications to provide additional protection for the privacy of law abiding Americans," Mr. Weich wrote, adding that "the administration is willing to consider such ideas, provided that they do not undermine the effectiveness of these important authorities."
One of the witnesses Democrats have invited to testify at both hearings is Suzanne E. Spaulding, who has worked for lawmakers of both parties as a former top staffer on the House and Senate Intelligence committees. Mrs. Spaulding said she would urge Congress to tighten restrictions on when the F.B.I. could use the Patriot Act powers.
The rapid build-up of domestic intelligence authorities after the Sept. 11 attacks, she said, had overlooked "important safeguards," which has resulted "in a greater likelihood at a minimum of the government mistakenly intruding into the privacy of innocent Americans, and at worst having a greater capability of abusing these authorities."
Still, she acknowledged, the public record contains scant evidence that the F.B.I. has abused its powers under the three expiring Patriot Act sections. And it remains to be seen whether a majority in Congress will welcome undertaking a potentially heated debate over national security in the midst of already wrenching efforts to overhaul the nation's health insurance system.
Republicans invited Kenneth L. Wainstein, a former assistant attorney general for national security for the Bush administration, to testify at both Patriot Act hearings.
"We have to be careful not to limit these tools to the point that they are no longer useful in fast-moving threat investigations," Mr. Wainstein said. "There is an important place for oversight of national security tools, and that oversight is being exercised by Congress and by the federal judges on the Foreign Intelligence Surveillance Court."
The first such provision allows investigators to get "roving wiretap" court orders authorizing them to follow a target who switches phone numbers or phone companies, rather than having to apply for a new warrant each time.
From 2004 to 2009, the Federal Bureau of Investigation applied for such an order about 140 times, Robert S. Mueller, the F.B.I. director, said at a Senate Judiciary Committee hearing last week.
The second such provision allows the F.B.I. to get a court order to seize "any tangible things" deemed relevant to a terrorism investigation - like a business's customer records, a diary or a computer.
From 2004 to 2009, the bureau used that authority more than 250 times, Mr. Mueller said.
The final provision set to expire is called the "lone wolf" provision. It allows the F.B.I. to get a court order to wiretap a terrorism suspect who is not connected to any foreign terrorist group or foreign government.
Mr. Mueller said this authority had never been used, but the bureau still wanted Congress to extend it.
Several other lawmakers are expected to file their own bills addressing the Patriot Act and related surveillance issues in the next several weeks.
Many of the proposals under discussion involve small wording shifts whose impact can be difficult to understand, in part because the statutes are extremely technical and some govern technology that is classified.
But in general, civil libertarians and some Democrats have called for changes that would require stronger evidence of meaningful links between a terrorism suspect and the person whom investigators are targeting.
In the same way, some are proposing to use any Patriot Act extension bill to tighten when the F.B.I. may use "national security letters" - administrative subpoenas that allow counterterrorism agents to seize business records without obtaining permission from a judge. Agents use the device tens of thousands of times each year.
The Patriot Act section that expanded the F.B.I.'s power to issue those letters is not expiring, but they have become particularly controversial because the Justice Department's inspector general issued two reports finding that F.B.I. agents frequently misused the device to obtain bank, credit card and telephone records.
Finally, some civil libertarians want lawmakers to revisit a June 2008 law in which Congress granted immunity from civil lawsuits to telecommunications companies that assisted President George W. Bush's program of surveillance without warrants, and that adjusted federal statutes to bring them into alignment with a form of that program.
As a senator, Mr. Obama voted for that bill, infuriating civil libertarians.
The bill filed Sept. 17 - which is championed in particular by two Democratic senators, Russ Feingold of Wisconsin and Richard J. Durbin of Illinois - would repeal the immunity provision.
The measure would also tighten statutory restrictions to ban the "bulk collection" of phone calls coming into the United States from overseas. Some security specialists say that they doubt the national security agency has that capability today, but that it could become feasible as classified technology advances.
"Every single member of Congress wants to give our law enforcement and intelligence officials the tools they need to keep Americans safe," Mr. Feingold said in a statement when filing the bill. "But with the Patriot Act up for reauthorization, we should take this opportunity to fix the flaws in our surveillance laws once and for all."
But changes to the hard-fought 2008 legislation on the Foreign Intelligence Surveillance Act, or FISA, could provoke fierce opposition from Senate conservatives. Senator Christopher S. Bond, Republican of Missouri and vice chairman of the Senate Intelligence Committee, strongly objected to revisiting that law.
"Our terror fighters need the tools and legal authorities to track terror suspects quickly, before they strike," Mr. Bond said. "Unfortunately, this bill would render our critical warning system useless by unraveling the bipartisan FISA provisions Congress passed last year."