A major supporter of the National Security Agency’s anti-terrorism surveillance program, which allows the bulk collection of Americans’ phone records, is pushing for an extension of the program, setting up a battle with critics who argue that Congress must fix the current law or let it expire.

"This has been a very important part of our effort to defend the homeland since 9/11," Senate Majority Leader Mitch McConnell said Sunday while defending the program in an interview on ABC's “This Week.” "We know that the terrorists overseas are trying to recruit people in our country to commit atrocities in our country."

McConnell, R-Ky., introduced a bill Thursday night that would temporarily renew the expiring provisions of the Patriot Act for two months.

The renewal would buy time for the Senate to debate, specifically, Section 215 of the Patriot Act, which authorizes the government to collect personal records without a warrant and has been the target of controversy since NSA contractor Edward Snowden revealed in 2013 that it was being used by the NSA to capture and retain millions of Americans’ personal phone records.  

The provisions are currently scheduled to sunset on June 1.

Meanwhile, the House on Wednesday passed the USA Freedom Act, a bipartisan bill lawmakers said would end the NSA’s ability to use Section 215 for that type of data collection. Instead, it would allow private telecom companies to keep the records. Federal law enforcement would have to get a court order proving a link to a specific criminal investigation to collect such phone record data, and must use specific search terms to get permission to pore through the information.

"This has been a very important part of our effort to defend the homeland since 9/11."

- Senate Majority Leader Mitch McConnell

The bill, sponsored by Rep. James Sensenbrenner, R-Wis., and Rep. John Conyers, D-Mich., passed by a margin of 338-88.  

This sets up a fight in the Senate with McConnell, who supports renewing the Patriot Act provisions, including Section 215, with no changes. He is supported by a number of senators, including Marco Rubio, R-Fla., and Tom Cotton, R-Ark., both of whom have publicly advocated a “clean” renewal of the Patriot Act. Still, McConnell is opposed by a number of Democrats and libertarian-leaning Republican members of the majority, like Sens. Ted Cruz, R-Texas, and Mike Lee, R-Utah. Sen. Rand Paul, R-Ky., who McConnell is supporting for the GOP presidential nomination in 2016, has said he will filibuster any attempt to renew the act without reforms.  

“We are going to demand amendments and we are going to make sure the American people know that some of us at least are opposed to unlawful searches," Paul told The New Hampshire Union Leader this week.  

"Everybody threatens to filibuster. We'll see what happens," McConnell said Sunday on “This Week.” "But we're talking about the security of the country here. This is no small matter."

Extra time to debate it might be necessary, Sen. John Cornyn, R-Texas, acknowledged to reporters on Thursday. The Senate also is grappling with Congress’ say in the Iran nuclear deal, and the Trans Pacific Partnership (TPP) fast track trade deal – two things McConnell has said need to be settled first, plus the authorization of highway funding.  

“There’s a range of views” on the NSA,” Cornyn said, according to The Hill newspaper. “I don’t know how you get all that done plus (the highway bill) before we break.”  The Senate is scheduled to go on break from May 23-31, according to its calendar.

The phone data collection program had been a secret until Snowden leaked documents proving its existence nearly two years ago. In that leak to the press, he showed that the NSA had been collecting millions of phone records since 9/11 – not the conversations, but dates, times and numbers – for the purpose of surveillance. The 2nd Circuit Court of Appeals ruled the program illegal on May 7, saying, "the [Patriot Act provisions] have never been interpreted to authorize anything approaching the breadth of the sweeping surveillance at issue here.”  

The court did not go so far as to halt the program with an injunction, but left it to Congress to pass reforms.  

Given these legal implications, and the fact the House is overwhelmingly in favor of changes, McConnell’s “clean” alternative and his attempt to delay matters will likely hit resistance, said Steve Vladeck, an American University law professor who teaches constitutional and national security law.  

“If the Senate doesn’t pass something close to the USA Freedom Act, then all hell breaks loose,” he predicted in an interview with FoxNews.com. "The June 1 deadline is looming, it’s just a couple of legislative days away.”  

A tougher version of the USA Freedom Act passed the House last year, but failed to get the 60 votes necessary in the Senate to proceed to a floor debate.  

But even the USA Freedom Act has its own detractors, mainly critics who believe Section 215, which allows the government to secretly comb personal records without warrant, should expire. While the American Civil Liberties Union has not endorsed or opposed a specific set of reforms, it warned House members ahead of its vote that the Sensenbrenner/Conyers bill is lacking a number of privacy protections and includes loopholes through which the government could still engage in bulk surveillance.  

“Though an improvement over the status quo in some respects, the USA Freedom Act does not go far enough to rein in NSA abuses,” the ACLU said in a May 12 letter to the House. In actuality, critics suggest, the USA Freedom Act may serve to codify the very activities the court was warning against.   

Fox contributor Judge Napolitano agreed, calling it a Band-Aid, that “would actually legitimize all spying, all the time, on all of us in ways that the Patriot Act fails to do.”  

Vladeck said the critics have a point. "There is no question that the USA Freedom Act is better than the McConnell [clean] bill, but I also think there is no question that the act that passed the House doesn’t go nearly as far as other reform bills that have been introduced,” he said. “The question is now: What kind of compromise is everyone going to be happy with?”

Libertarians say they won't be happy until all of Section 215, if not the entire Patriot Act, is scrapped entirely. They say its sweeping law-enforcement powers have tipped the balance against innocent Americans' civil liberties without providing a clear rationale for their usefulness in terror investigations.  

“It’s your classic conundrum, whether the Congress should swallow the bad in order to get the good. It’s time to get beyond fighting in the weeds here,” said Jacob Hornberger, president of the Future of Freedom Foundation, in an interview with FoxNews.com.  

“It’s time for the American people to look beyond that and say, ‘Is this what we want for a free society? Do we really need a NSA? Do we even need a Patriot Act?’ My argument is we don’t. These are antithetical to a free society.”  

The Hill reported Thursday that supporters of the USA Freedom Act are already lining up against any temporary extension of the Patriot Act on the House side, which would be required in order to thwart the June 1 deadline.  

Nevertheless, there are national security hawks in the Senate who will likely embrace the extra room for debate, especially if they need more time to get members on board to pass a clean renewal. “Contrary to irresponsible rumors, the [bulk surveillance] program is lawful, carefully monitored, and protects personal privacy,” said Sen. Cotton and Rep. Mike Pompeo, R-Kan., in an Op-Ed on Friday.  

“As members of the House and Senate Intelligence Committees, we have carefully studied this program and are convinced that it’s an integral tool in our fight against terrorism.”