The US Senate on Tuesday advanced a landmark measure that ends the government's bulk data collection of Americans' phone records, while reauthorizing other surveillance powers that lapsed this week.
The USA Freedom Act would halt the National Security Agency's dragnet of telephone data from millions of Americans who have no connection to terrorism, the most controversial surveillance program among several signed into law in the wake of the 9/11 attacks on the United States in 2001.
The reform bill would shift the storage of the metadata from the NSA to the telephone companies, allowing authorities to access the information only with a warrant from a secret counterterror court that identifies a specific person or group of people suspected of terrorist ties.
It would also reinstitute roving wiretaps and lone-wolf tracking, two powers that expired at midnight Sunday when the Senate was unable to get an extension before the sunset of key national security provisions in the USA Patriot Act.
The Freedom Act has already passed the House of Representatives. It advanced easily in the Senate on an 83-14 vote.
If it reaches final Senate passage as is, it goes to President Barack Obama, who supports the measure.
But if the Senate amends it later Tuesday, as it might, the bill returns to the House where lawmakers would need to approve the changes.
House leaders have warned that could delay final passage, or risk a collapse of the reform bill altogether, which means several national security authorizations may expire for good.
"If the Senate changes it, it would bring a real challenge inside the House," number two House Republican Kevin McCarthy told reporters Tuesday.
"The one thing the Senate should find this morning is common ground the way the House did, and send it to the president" without changes, he said.
The amendments which Senators will vote on later Tuesday include extending from six months to one year the transition period for switching data storage from the NSA to the telecommunications companies.
A second amendment would require the director of national intelligence to review the system.
One change would strip out a provision that declassifies rulings by the secret Foreign Intelligence Surveillance Court, a move critics have argued would erode important transparency that was built into the original Freedom Act.