WASHINGTON (CNN) -- The Senate voted Tuesday to give immunity to telecommunications companies that helped the federal government eavesdrop on suspected terrorists after the September 11 attacks.
Lawmakers are debating an update to the Foreign Intelligence Surveillance Act this week.
An attempt to remove language granting retroactive immunity from the intelligence bill failed by a 31-67 vote.
A final vote is expected late Tuesday on legislation meant to update the 30-year-old Foreign Intelligence Surveillance Act, or FISA, the law that regulates the intelligence community's surveillance practices.
Lawmakers are facing a tight deadline to complete voting on the bill. A temporary update to FISA expires at the end of the week.
The temporary bill allows the intelligence agencies to monitor foreign-to-foreign communications involving suspected terrorists without a warrant even if they come through telecommunication switches in the United States.
The bill being debated in the Senate would grant the intelligence agencies permanent authority to conduct foreign intelligence without a warrant.
The House already has passed a version of the bill, but it does not include retroactive immunity for the telecommunication companies.
The House version also gives the FISA court more oversight over the program.
Differences between the House and Senate legislation would have to be reconciled before a bill could be sent to the White House for the president's signature.
President Bush has threatened a veto if the bill does not include the immunity clause.
Sen. Dick Durbin of Illinois, the No. 2 Democrat in the Senate, said there would be an intense effort to reach a quick compromise with the House.
"We're hoping to move it expeditiously," he said. "I don't know anything about the timing or the nature of it, but there's a genuine good-faith effort to try to find some common ground between the House and the Senate, pass it, and send it to the president."
In January, the House of Representatives and Senate passed a 15-day extension to the Protect America Act, which was hastily passed in August when the Bush administration warned of gaps in its ability to monitor suspected terrorists.
But prospects for a permanent law seem as daunting now as they did last summer when Congress agreed to the temporary measure so lawmakers could try to reconcile their differences.
The question of immunity has been among the most heatedly debated points of the bill.
AT&T, Verizon and other companies are believed to have provided information to aid the National Security Agency's no-warrant wiretapping program. The program, which Bush authorized in the wake of the 9/11 attacks, monitored communications involving suspected al Qaeda members and people in the United States.
"It is dangerous and setting a precedent," Sen. Chris Dodd, D-Connecticut, said during debate Tuesday. He argued the question of whether the companies' actions violated the law should be decided by the courts.
The telecommunication firms are facing more than 40 lawsuits alleging the privacy of their customers was violated when their records were allegedly turned over to the government. The companies have refused to comment on their activities related to the government.
Before the presidential directive authorizing that program, the NSA had to get a warrant from a special surveillance court to eavesdrop on such conversations.
Sen. Orrin Hatch, R-Utah, a member of the Senate Judiciary and Intelligence committees, said without immunity, the firms would turn down future requests for help.
"They patriotically complied with the top government request to cooperate so that we could interdict phone calls from terrorists," he said. "And frankly, if we do not give retroactive immunity, there is not a general counsel of any of these companies that would [again] expose their company to the ... litigation that has come since."
Proponents also argue the companies' efforts are essential in helping uncover terrorist leads.
"The intelligence community doesn't have the facilities to carry out the kind of international surveillance needed to defend this country since 9/11," Vice President Dick Cheney said in a speech last week to the Heritage Foundation. "In some situations there is no alternative to seeking assistance from the private sector. This is entirely appropriate."
Civil rights advocates, including the group Democracy for America, counter that immunity is a "get out of jail free card" for what they call "illegal spying on Americans." E-mail to a friend
All About Terrorism • U.S. Foreign Intelligence Surveillance Court