Rand Paul came under mounting pressure to prevent a full lapse in US surveillance authorities on Sunday, as allies of the Kentucky senator joined hawks at the opposite end of the political spectrum in calling for the swift passage of the compromise USA Freedom Act.

As the clock ticked down to the midnight expiry of existing Patriot Act provisions, an unprecedented coalition of civil libertarians and security establishment figures lined up to support what many see as the least worst solution to the problem of balancing privacy and national security.

The USA Freedom Act would ban the government collection of bulk phone records first revealed in the Guardian by Edward Snowden, forcing the National Security Agency (NSA) to make specific requests from telecom providers instead. It is supported by the Obama administration.



But the compromise reform bill is seen by Senator Paul, a candidate for the 2016 Republican presidential nomination, and several key privacy groups as an insufficient response to the wider Snowden disclosures and the Kentucky Republican has said he will not let a vote proceed quickly through the Senate unless party leaders agree to debate several amendments.

The impasse threatens to instead force a much wider lapse of NSA powers when the disputed Patriot Act provisions expire under a “sunset” clause at midnight, something the White House has claimed would put ongoing terrorism investigations at risk.

On Sunday morning, the Utah Republican senator Mike Lee, a sponsor of the USA Freedom Act and close ally of Paul, distanced himself from his colleague’s tactics.

“Although he and I share a similar concern, I don’t agree with his approach,” Lee said in an interview on CNN.

Asked if Paul’s actions could delay passage of the USA Freedom Act until Wednesday and force a 72-hour suspension of NSA legal authority, Lee said: “I hope not. I think that would be unfortunate and I think it would be unnecessary and that’s why I would like to try to get it passed today.”

A spokesman for Oregon Democrat Ron Wyden told the Guardian on Sunday: “Senator Wyden believes the Senate should act on the USA Freedom Act as soon as possible.”

The bill’s lead sponsor, Democratic senator Patrick Leahy, argued there was still time for the Senate to hear some amendments to the USA Freedom Act on Sunday evening – suggesting a potential route for both Paul and Senate majority leader Mitch McConnell to climb down.

.@SenatorLeahy, in stmt to be repeated tomorrow: Let Paul have his amendments debated http://t.co/Vs8wIViEoA pic.twitter.com/uf0GSKT8RP — Dustin Volz (@dnvolz) May 30, 2015

Like Lee and Leahy, Wyden places responsibility for the cliff-edge showdown on Senate Republican leaders who have deliberately delayed a vote in the hope of using the deadline to force a simple extension of the Patriot Act instead.

“Senate Republican leaders chose to run out the clock until expiration of these provisions was the only likely outcome, and they bear full responsibility for where the Senate stands today,” said Wyden’s office.

“We have known it was coming for the last four years,” said Lee, who said “governing by cliff” was a bad Senate habit that had to stop. “That’s why we came up with this bill so it could be introduced and passed well in advance of this deadline.”

Nevertheless, Lee was confident there were now enough votes to pass the USA Freedom Act, which last week fell three senators short of the 60-vote hurdle.

“I do believe we have the votes,” said Lee. “So at this point the question is not really whether we get this passed but when it will happen: tonight or Wednesday, or sometime between then.”

Despite the ability of Senate leaders to eventually force through a vote against his wishes, Senator Paul was in defiant mood, reveling in his lonely stand against both parties and ability to force a temporary lapse in the Patriot Act provisions.

“On Sunday I will stop the illegal NSA spying,” he wrote in an opinion piece for Time magazine.

“We should not be debating modifying an illegal programme. We should simply end this illegal programme,” he added.

In comments to supporters in South Carolina and a statement issued to Politico, Paul hinted that he would not give majority leader McConnell the unanimous consent needed to move to a final vote on USA Freedom Act when the Senate resumes for an unusual Sunday session at 4pm.

“I do not do this to obstruct,” he said. “I do it to build something better, more effective, more lasting, and more cognisant of who we are as Americans.”

If McConnell meets Paul’s demands and allows amendments to be debated before the USA Freedom vote, he could anger many hawks in his party who believe the bill is deeply flawed and favour reauthorising existing powers under the Patriot Act.

“It’s not a violation of civl liberties,” insisted presidential hopeful Jeb Bush in an interview with CBS, in which he warned the nation’s security would be endangered if the bulk collection programme was allowed to expire.

“There is no evidence, not a shred of evidence that the metadata programme has violated anybody’s civil liberties,” Bush claimed.