A pair of senators on Friday released their bipartisan proposal to renew a powerful surveillance authority for collecting foreign intelligence on U.S. soil, but with a new brake on the government’s ability to access the data.

The bill from Sens. Patrick J. Leahy (D-Vt.) and Mike Lee (R-Utah) would require government agencies to obtain a warrant before reviewing communications to or from Americans harvested by the National Security Agency under the surveillance authority known informally as Section 702.

The measure stands little chance of passage. But, some Senate aides said, it may pressure lawmakers to insist on privacy-enhancing reforms as they look toward an end-of-year deadline to reauthorize the data-collection program — the intelligence community’s highest legislative priority this year.

Leahy and Lee’s proposal is the fifth piece of legislation to propose some form of restriction on the government’s data-gathering authority under Section 702 of the Foreign Intelligence Surveillance Act. The law enables the NSA to collect from U.S. companies the emails and communications of foreigners located overseas.

Those foreigners, however, may also be communicating with Americans, and the communications are stored in databases that agencies, including the FBI, can query.

That has prompted concerns from civil liberties advocates that the program enables domestic spying and the demand for a warrant to search or view Americans’ data.

The bill is modeled after a House Judiciary Committee bill, which also requires a warrant to review any communications returned in response to a query.

But the House bill applies only in criminal cases. The Senate version covers national security cases, too.

Lee and Leahy’s measure also would permanently ban a subset of Section 702 surveillance — collection that the NSA recently ended voluntarily but has said it would reinstate if it could find a way to comply with the federal surveillance court that oversees the law.

“This bill implements some much needed reforms to our surveillance laws that will better protect law-abiding Americans’ privacy in a manner consistent with the Fourth Amendment,” Lee said in a statement.

Congressional leaders have acknowledged that it will be necessary to impose some restrictions on the NSA’s authority to secure support for extending the program.

But they are hoping that lawmakers will back an extension that imposes fewer restrictions than the House Judiciary bill.

Last month, the Senate Intelligence Committee approved a Section 702 bill that avoids warrants. Instead, it gives the FBI one business day to submit a request to the Foreign Intelligence Surveillance Court to review data turned up by an FBI query for information on a U.S. person. The court would have two business days to rule on the request’s legality.

Senate leaders are now exploring ways to incorporate that legislation into a must-pass, end-of-year spending bill next month, or to adopt a short-term extension of the law that will give them a chance to revisit the measure next year.

But doing so depends on securing agreement from leaders in the House, where intelligence committee lawmakers have yet to formally weigh in on how to reauthorize the program.

That panel’s leaders want fewer restrictions than the House Judiciary bill to protect the intelligence agency’s powers.

Senate Republican leaders are also hopeful that the House Intelligence Committee can come up with a measure that is consistent with its Senate counterpart’s, which they believe can secure significant bipartisan Senate support.

The Leahy-Lee bill gives privacy advocates a new measure to rally around as congressional leaders head into late-stage negotiations.

Its warrant requirement is based on a proposal from California Democratic Sens. Dianne Feinstein and Kamala D. Harris.

ellen.nakashima@washpost.com