In the early hours of Saturday morning, the United States Senate halted the advance of a compromise bill that aims to end metadata collection under Section 215 of the Patriot Act.

Given that the USA Freedom Act cannot seemingly advance in the Senate, there is a very strong possibility that the relevant portions of the law will expire as of the stroke of midnight on June 1, 2015.

The Senate voted 57-42 to reject the measure, and also immediately rejected a 60-day extension of the existing law on a 54-45 vote. The bill, which previously passed the House of Representatives just over a week ago, has the support of the White House.

The House of Representatives had already gone into recess for a week over the Memorial Day holiday on Monday. Meanwhile, Senate was sent into recess shortly after the votes, but will return for a rare Sunday session on May 31.

"There is no Plan B," White House spokesman Josh Earnest told reporters earlier on Friday.

"The fact is we’ve got people in the United States Senate right now who are playing chicken with this," he added. "And to play chicken with that is grossly irresponsible."

Among other revisions, the USA Freedom Act ends the bulk phone database but doesn't include many other wished-for reforms, such as a privacy advocate at the Foreign Intelligence Surveillance Court, which was in an earlier version of the bill. It also doesn't include "minimization" procedures meant to make sure the government purges information about people not related to its investigations.

Some critics, including the Electronic Frontier Foundation, say that the USA Freedom Act does not go far enough to provide meaningful surveillance reform.

According to Politico, Senate Majority Leader Mitch McConnell "announced that the Senate would be back in session on May 31 to resolve the Patriot Act standoff—just hours before the critical provisions are poised to sunset."

Getting ready

Sen. Rand Paul (R-Ky.), who previously held the chamber’s floor for nearly 11 hours in protest of the USA Freedom bill, lauded the delayed decision.

The Senate will return one week from Sunday. With your help we can end illegal NSA spying once and for all. — Dr. Rand Paul (@RandPaul) May 23, 2015

One staunch ally of Paul's on this issue, Sen. Ron Wyden (D-Ore.), issued a statement to the media not long after the Saturday vote.

“This week Americans must continue to speak out against government interference in their private communications," he said.

"A decade after intelligence leaders secretly created a program to violate the privacy of millions of law-abiding Americans, we are on the verge of finally shutting it down. I’m confident that when Americans and the US Congress debate mass surveillance in the light of day we will finally close the door on the worst violations of Americans’ privacy."

Prior to the Saturday morning votes, which took place around 1am Eastern Time, the Department of Justice had circulated a memo saying: "After May 22, 2015, the National Security Agency will need to begin taking steps to wind down the bulk telephone metadata program in anticipation of a possible sunset in order to ensure that it does not engage in any unauthorized collection or use of the metadata."