The Senate on Tuesday rejected a measure to reform the National Security Agency's surveillance program in a 58-42 vote.
The defeat of the legislation to stop the government's bulk data collection program will put off legislation responding to Edward Snowden's leaks about the controversial programs until next year.
Most Democrats backed Leahy, but he was able to win over few Republicans beyond his three GOP co-sponsors, who included Sen. Ted Cruz (R-Texas).
Senate Minority Leader Mitch McConnell (R-Ky.) may have dealt the legislation a fatal blow when he used a floor speech on Tuesday to argue that passage of the legislation would hurt U.S. efforts to stop terrorist groups.
“At a minimum, we shouldn’t be doing anything to make the situation worse,” McConnell said ahead of the vote. “Yet, that’s just what this bill would do.”
Defenders of the bill on both sides of the aisle maintained that it would safeguard Americans’ privacy rights without hurting the country’s ability to fight terrorists.
“It enhances privacy and civil liberties protections,” Senate Majority Leader Harry Reid (D-Nev.) said. “And it continues to give the U.S. intelligence community the ability to gather the information it needs to keep America safe.”
The bill represented the most dramatic overhaul of U.S. intelligence powers in more than a decade, and the only substantive legislation passed in the wake of Snowden’s disclosures nearly a year and a half ago.
It would have ended the NSA's ability to collect records about Americans’ phone calls in bulk, and would have required that the agency obtain a court order before asking private phone companies for their records about suspected terrorists.
It would also add a team of privacy advocates to the secretive federal court overseeing intelligence activities — which currently only hears arguments from the government — and requires the government to disclose how many people were wrapped up in its searches.
Technology companies and many privacy advocates support the bill, saying it could be the first key legislative blow against the NSA.
Leahy expressed his disappointment over the defeat immediately after the final roll call was announced.
"If we do not protect our Constitution, we do not protect our country and we do not deserve to be in this body," Leahy said after the vote.
Besides Cruz, Republican Sens. Mike Lee (R-Utah), Dean Heller (Nev.) and Lisa Murkowski (Alaska) backed his bill. Senate Intelligence Committee Chairwoman Dianne Feinstein (D-Calif.) also supported the bill.
Sen. Bill Nelson (D-Fla.), though, opposed the measure.
The vote is a stunning defeat for critics of the spy agency, who have fought to rein in the NSA for more than a year.
Failure of Leahy’s bill is sure to set up a dramatic fight early next year, as one of the first tests of a new Republican congressional majority.
Without reauthorization in some form, the NSA’s phone records program is set to end entirely next June. Leaders of the nation’s intelligence agencies have warned that would cripple their ability to track terrorists and would be disastrous for America’s national security.
"If we do not pass this bill, we will lose this program," Feinstein warned her colleagues on the Senate floor on Tuesday.
As the 2016 presidential campaign begins to kick into high gear, the debate could offer Sens. Rand Paul (R-Ky.), Ted Cruz (R-Texas) and Marco Rubio (R-Fla.) — all potential candidates with different positions on the NSA — the opportunity to spar on the Senate floor.
In urging lawmakers to pass the bill now on Monday, the White House warned that putting it off until next year would lead to “brinksmanship and uncertainty” in the new Republican Congress.
The failure is also a serious setback to the technology industry, which lobbied long and hard to pass a bill.
Companies say that Snowden’s revelations about the NSA have cost them massively in terms of trust around the world. One estimate pegged the profit loss at $180 billion by 2016.
This post was updated at 8:35 p.m.