Ten senators have the future of the Patriot Act in their hands.

They will be the ones who can make or break any deal on whether or not to reauthorize or reform the National Security Agency's bulk spying programs—or to continue down a path to letting the Patriot Act Section 215 language lapse altogether.

In theory, the Senate is out until Sunday afternoon, but staffers will be burning up the phone lines until then—and these are the senators who matter the most. And if reformers want to bolster their cause, they will need to win over three of them to get the USA Freedom Act from 57 votes to a filibuster-proof 60.

Worth noting is that seven of the ten senators below are up for reelection in 2016—some in close races—which could nudge the Republicans left on the issue.

Rand Paul continues to be one of the most intriguing—and disruptive—players in the fight over the NSA's surveillance programs. The Kentucky Republican's 10-and-a-half-hour "filibuster" got him closer to his goal of pushing provisions of the Patriot Act toward expiration, and he, along with Democratic Sens. Ron Wyden and Martin Heinrich, stood and objected to Majority Leader Mitch McConnell's proposals for shorter and shorter-term extensions of the provisions on Saturday morning.

But while Wyden and Heinrich support the Freedom Act as worthwhile reform, Paul says it doesn't go far enough—and he voted against it. Paul has repeatedly asked to add several amendments to the USA Freedom Act, but he has not said whether he would vote for the reform package if they were allowed consideration.

During his objection to McConnell's short-term pushes, Paul said he had asked leadership for a compromise to allow a simple majority vote on just two of his amendments, which would normally need to clear a 60-vote hurdle. But leadership refused that request, and Paul responded by refusing to allow any short-term extension to go forward.

It is not clear what two amendments Paul wants to put to a vote, and his office did not respond to multiple requests for clarification. If his amendments do earn a vote, Paul may allow the Freedom Act to go forward for another vote—even if he again votes against it.

Angus King of Maine, an independent who caucuses with the Democrats, was the only non-Republican to vote against the Freedom Act. His breaking rank was particularly notable given his vote for an earlier, wider-reaching version of the Freedom Act last year. He also voted down McConnell's two-month extension.

King told National Journal he had concerns that the Freedom Act did not possess a data-retention mandate, which is widely viewed as a "poison pill" for tech companies and privacy advocates. Such a mandate is part of the "compromise" bill being pushed now by Democratic Sen. Dianne Feinstein on which King is a cosponsor. But Feinstein voted for the Freedom Act, leaving open the possibility that she could cajole King to support the measure if it comes up for another vote.

Michael Enzi of Wyoming was the only senator who was absent during the votes last week on the Freedom Act and the short-term extension. His name was on a last-minute short list of "targets" being circulated among pro-reform groups the day leading up to the vote, and for good reason: Enzi, like many of his fellow Republicans who voted for the Freedom Act, hails from a more libertarian-leaning Western state and has criticized NSA spying in the past.

Enzi's office late Tuesday provided a statement from the senator indicating he believes surveillance reform is necessary—but that the Freedom Act might not be the best vehicle for it.

"The NSA needs to focus on suspected terrorists," the statement read. "If it wants more information on someone, it should get a warrant from an independent judge, not one that it signs itself. Warrants should be targeted at information relevant to an investigation."

Enzi said he appreciated his colleagues' efforts on crafting legislation to end bulk data collection and narrow what the NSA can search, but suggested more work needs to be done.

"I'm afraid, though, that these reforms still weigh too heavily in favor of the government rather than individuals," Enzi said. "To be safe, we need to lean on the Constitution because if we tear down our basic rights to be safe, we'll lose what so many have fought for."

Mark Kirk switched his vote from a "yes" to a "no" Saturday morning, surprising many observers who thought the Illinois Republican had come around to the reform bill. Freedom Act supporters said they believe Kirk may still be in play. Kirk, who will face an uphill challenge in 2016 against Illinois Rep. Tammy Duckworth, has played up his centrist credentials to gain favor in his blue home state.

Bill Cassidy of Louisiana was a top target of pro-reform groups, but his "no" vote on the Freedom Act all but sealed the reform measure's fate. The freshman Republican's opposition was especially devastating to the bill's backers, as he had voted for an earlier version of the Freedom Act last year when he was a member of the House. Reformers hope they might still be able to convince Cassidy, who was once a member of the House Tea Party Caucus, to help the Freedom Act get to 60 if it gets another vote.

Kelly Ayotte, a New Hampshire Republican, was among a bipartisan group of about a half-dozen senators to attend a meeting in the White House Situation Room earlier in the week to discuss the Patriot Act standoff. But despite the administration's outreach, Ayotte voted against the Freedom Act. Reformers continue to hope Ayotte's vote is malleable, however, especially given that she hails from the "Live Free or Die" state. Ayotte could be in for a tough election in 2016 if popular New Hampshire Governor Maggie Hassan decides to run.

Republican Sens. Jerry Moran of Kansas and Mike Crapo of Idaho voted no on both the USA Freedom Act and McConnell's proposed two-month extension. This puts them in rare company with Sen. Paul, who says he opposes any extension of the Patriot Act provisions, Sen. King, who wants reform but believes the Freedom Act needs a data-retention mandate to have any teeth, and McConnell, who switched his vote on the two-month extension from "yes" to "no" for procedural reasons.

It is not clear what Moran's and Crapo's motives are for opposing both options—and neither senator's office responded to requests for comment. Both senators have not been particularly vocal on surveillance issues either, leaving it unclear if they, like Paul, believe the Freedom Act needs to be bolstered, or if they fear that it could undermine national security.

Pat Toomey, who also appeared on the reform activists' target list, refused to say which way he was leaning prior to the double-barrel votes on the Freedom Act and the short-term extension. The Pennsylvania Republican ultimately voted against the Freedom Act's reforms, and for McConnell's two-month extension of the Patriot Act. Come 2016, Toomey will be up against Pennsylvania Rep. Joe Sestak, whom he narrowly defeated in 2010.

John Boozman, a Republican from Arkansas, would not say where he was leaning on the Freedom Act before the vote. On Friday, he voted against the NSA reform bill, and for the proposed two-month extension of the Patriot Act. Still, many pro-reform advocates continue to see Boozman as a potential swing vote.

This article has been updated with details about senator's 2016 election challenges.