This article is from the archive of our partner National Journal

Now that Congress has passed the USA Freedom Act, a surveillance overhaul bill that will shutter the National Security Agency's bulk gathering of U.S. call data—having done so while shutting down attempts from the Senate Majority Mitch McConnell to weaken it—reform-minded legislators are emboldened.

But while reformers hope Tuesday's victory is an appetizer to a multiple-course meal to rein in the NSA, security hawks—many of them Republicans vying for the White House—hope to halt the post-Snowden momentum behind surveillance reform. And some already are talking about unraveling the Freedom Act.

"What you are seeing on the floor of the Senate is just the beginning," said Sen. Ron Wyden, a civil-liberties stalwart in the upper chamber who serves on the intelligence committee and has worked for more than a decade to reform government surveillance. "There is a lot more to do when—in effect—you can ensure you protect the country's safety without sacrificing our liberty."

Wyden used the Freedom Act's passage to call for additional intelligence-gathering reforms that he has long advocated, such as closing the so-called "backdoor search loophole" that allows U.S. spies to "incidentally" and warrantlessly sweep up the email and phone communications—including some content—of Americans who correspond with foreigners. He added he plans to move quickly on reworking Section 702 of the Foreign Intelligence Surveillance Act, before Congress is up backed up against its renewal deadline in 2017.

The Oregon Democrat also supports tech companies in their ongoing tussle with the administration over smartphone encryption as a key priority. While Google and Apple have begun to build their phones with "too-tough-to-crack" encryption standards, the FBI has warned that the technology locks out the bad guys and the good—and can impede law-enforcement investigations.

Wyden and his allies, though, are bumping up against an impending presidential campaign, where many Republicans will jockey with one another to look toughest on national security.

Few issues divide the GOP White House contenders more than NSA surveillance, as defense hawks such as former Florida Gov. Jeb Bush and Sen. Marco Rubio continue to defend the NSA bulk metadata program as necessary to protect the homeland, while libertarian-leaning agitators such as Sens. Rand Paul and Ted Cruz warn voters of the privacy perils associated with the government's prying eyes.

Rubio, who has said he'd prefer that the NSA's phone dragnet be made permanent, issued a statement after the Freedom Act's passage saying it fell to the next president to undo its policies.

"The failure to renew the expiring components of the PATRIOT Act was a mistake," Rubio said in a statement after the vote. "The 'USA Freedom Act' weakens U.S. national security by outlawing the very programs our intelligence community and the FBI have used to protect us time and time again. "ŽA major challenge for the next president will be to fix the significantly weakened "Žintelligence system that the current one is leaving behind"Ž."

Paul, meanwhile, continues to fundraise on social media and in campaign emails off his hardline opposition to "illegal NSA bulk data collection." The Kentucky senator succeeded in drawing enormous attention to the issue by forcing a temporary lapse this week of the Patriot Act's spy authorities, and has vowed to limit the agency's mass surveillance practices "on day one" if elected president.

But Paul also was a major obstacle for the Freedom Act's passage, repeatedly voting against it and helping delay its consideration on grounds it didn't go far enough—and codified parts of the Patriot Act he thinks should stay dead.

Cruz, meanwhile, represented the middle ground and was a chief GOP backer of the legislation, setting up a potential argument with Paul on debate stages about who has done more to fight against mass surveillance. Any jockeying between the two will expose them to sniping from candidates on the other side of the debate, including potential candidate Chris Christie, the New Jersey governor, who often goes out of his way to condemn those who criticize government snooping. Rand Paul already has become a regular punching bag for the GOP field's security hawks.

Back on Capitol Hill, many of the same members who were trying to block reform warn that it only takes one security setback for Congress to stop taking powers away from the NSA.

"The next time there is a terrorist act within the United States, the same people are going to be coming to the floor seeking changes to the tools that our intelligence community, our law enforcement community has at their disposal because the American people will demand it," said Sen. Richard Burr, the chairman of the Intelligence Committee.

Sen. Susan Collins, who also serves on the intelligence panel, recognized that reforms and oversight will likely continue now that the USA Freedom Act has passed, but she said she's not so sure supporters of the Freedom Act won't have buyer's remorse down the line.

"I believe it is actually going to expose Americans' data to greater privacy risk and to vulnerability from computer data breaches," Collins said.

The momentum to end the NSA's phone dragnet snowballed over the past year and a half as two review panels deemed it ineffective. President Obama pledged to end it "as it currently exists" and a federal appeals court deemed it illegal.

But further reforms—such as to the Internet surveillance program known as PRISM, which Snowden also revealed—are likely to be tougher sells in Congress. For PRISM especially, that's in part because the program is considered more useful and because it deals primarily with surveillance of foreigners. U.S. tech companies that are subject to PRISM, including Facebook, Yahoo, and Google, have called for changes to the program. Yet when asked about whether he would work to take down PRISM, even Wyden bristled at the question.

"I am going to keep it to the three that I am going to change," Wyden said.

Even reformers outside the confines of the Senate recognize that ending PRISM is a complicated pursuit.

"It is not going to be quite as easy to drum up the same support," says Liza Goitein, codirector for the Liberty & National Security Program at the Brennan Center for Justice.

Though PRISM may prove difficult to upend, other efforts, such as a broadly supported push to update the decades-old Electronic Privacy Communications Act, may prove more palatable. Sens. Patrick Leahy and Mike Lee, the lead authors of the Freedom Act in the upper chamber, indicated their desire to move quickly on passing legislation that would update the law to require law enforcement obtain warrants before accessing the content of Americans' old emails.

The immediate next battlefield for civil liberties groups will find them on the defense, as they attempt to prevent legislation that would increase the sharing of certain cyber data among the private sector and the government in order to better fend off data breaches. Such proposals, which already passed the House and are likely to be before the Senate in the coming weeks, could grant the NSA access to more personal data, privacy advocates warn.

No matter how the looming debates shake out, for now, one thing is clear: the fight over the government's surveillance operations is far from over.

This article is from the archive of our partner National Journal.