Key Patriot Act anti-terror provisions, including bulk collection of Americans’ phone records, expire at midnight unless senators come up with an 11th hour deal in an extraordinary Sunday afternoon session.

Chances for that look all but nonexistent. GOP Sen. Rand Paul of Kentucky, who is running for president, vowed Saturday to force the bulk phone collection program to expire — and the Senate’s complex rules allow him to do just that, at least temporarily.

A House-passed bill backed by the White House that remakes the National Security Agency phone collection program is just three votes short in the Senate. But even if it picks up the needed support despite opposition from Senate Majority Leader Mitch McConnell, R-Ky., moving to a final vote requires the assent of all senators. Paul made crystal clear Saturday that he will not go along.

“I will force the expiration of the NSA illegal spy program,” Paul said in a statement. “Sometimes when the problem is big enough, you just have to start over.”

Paul cannot hold off a final vote indefinitely, just for a few days. But until the impasse is resolved, the NSA will lose its legal authority to collect and search domestic phone records for connections to international terrorists — the once-secret program revealed by agency contractor Edward Snowden.

Two lesser-known Patriot Act provisions also would expire: one, so far unused, that helps the bureau track “lone wolf” terrorism suspects unconnected to a foreign power, and another that allows the government to eavesdrop on suspects who continuously discard their cellphones.

The White House is raising dire warnings that letting the authorities expire would put Americans at risk.

“Heaven forbid we’ve got a problem where we could have prevented a terrorist attack or apprehended someone who is engaged in dangerous activity but we didn’t do so simply because of inaction in the Senate,” President Barack Obama said Friday. The White House-backed USA Freedom Act would keep the programs operational but shut down the bulk phone collection program over six months and give phone companies the job of maintaining records the government could search.

Civil libertarians dispute the White House’s warnings, arguing that the surveillance programs have never been shown to produce major results.

“A great deal of the ‘sturm und drang’ over expiration of the Patriot Act is overstated… The sky is not going to fall,” American Civil Liberties Union executive director Anthony Romero told reporters.

Paul’s hard-line opposition to the surveillance program has greatly complicated matters for fellow Kentuckian McConnell, who oversaw a chaotic late-night session last weekend where the Senate tried and failed to pass the House bill and several straight-up extensions of current law. Paul’s presidential campaign is aggressively fundraising on the issue, and a super PAC supporting Paul even produced an over-the-top video casting the dispute as a professional wrestling-style “Brawl for Liberty” between Paul and Obama — even though Paul’s main opponent on the issue is McConnell.

McConnell had little to say in response to Paul’s statement Saturday. “The leader has called the Senate back prior to the expiration of the expiring provisions to make every effort to provide the intelligence community with the tools it needs to combat terror,” said McConnell spokesman Don Stewart.

McConnell supports an extension of current law, but even if the Senate could agree to that Sunday the House is not in session and could not approve it and send it to the president.

The NSA already has begun winding down the phone collection program in anticipation that it will not be renewed. In order to ensure that the program has completely ceased by the time authority for it expires at midnight, the agency plans to begin shutting down the servers that carry it out at 3:59 p.m. Sunday. That step would be reversible for four hours — by which time it should be evident whether there’s any hope of a last-minute deal on Capitol Hill— but after that, rebooting would take about a day.

(AP)