Sen. Rand PaulRandal (Rand) Howard PaulHouse poised to vote on .3T spending bill Overnight Finance: Lawmakers race to finalize omnibus | What we know about funding bill | White House on board | Fed raises rates for first time under Powell Senate passes controversial online sex trafficking bill MORE (R-Ky.) has seized on the controversy surrounding National Security Agency surveillance programs, quickly emerging as perhaps their most high-profile opponent.

Government surveillance is an issue that's near and dear to his libertarian base, and one he’s advocated against for some time now. Following the revelations that the NSA has collected domestic phone records, Paul introduced a bill that would require a warrant before the government could seize such records, and has called the program "an astounding assault on the Constitution."

But Republican consensus on the issue is still emerging. While Paul’s opposition to the surveillance programs is likely to invigorate the libertarian and Tea Party base that helped him get elected to the Senate, it could ruffle some feathers in the GOP, as most lawmakers have thus far taken a cautious approach to evaluating the programs.

This issue crystallizes Paul’s dilemma heading into 2016: To make it through the Republican primaries, he’ll need to prove he can work with establishment Republicans while managing to avoid alienating his far-right base.

“To the extent that he's going to get worked up and really use it as something to campaign on, he's the face of the opposition to this situation,” said Tim Hagle, professor of political science at the University of Iowa.

Hagle said that Paul would have to answer for his position on the surveillance program if it eventually becomes counter to the mainstream, but that it would likely sell well in early primary states like Iowa and New Hampshire.

Iowa, with its conservative leanings and Tea Party faction, and New Hampshire, with its libertarian streak, are likely to be receptive to Paul’s outspoken opposition to the surveillance programs.

But establishment Republicans are walking a far finer line on the programs.

Speaker John BoehnerJohn Andrew Boehner4 reasons Mike Pompeo will succeed at Foggy Bottom The misunderstood reason Congress can’t get its job done GOP sees McCarthy moving up — if GOP loses the House MORE (R-Ohio) would only go so far as to call for an investigation into the scandal, and Sen. Marco RubioMarco Antonio RubioRussia leak raises questions about staff undermining Trump House members urge Senate to confirm Trump's NASA nominee Rubio: McCabe 'should've been allowed to finish through the weekend' MORE (R-Fla.), another potential 2016 contender, was even more tempered in his response, going so far as to say “programs like this have great utility.”

A Paul aide pushed back against the idea that the senator has trouble with the establishment, noting his close relationship with Senate Minority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellCollins: 'Extremely disappointing' ObamaCare fix left out of spending deal House poised to vote on .3T spending bill Budowsky: Stop Trump from firing Mueller MORE (R-Ky.). The aide balked at the suggestion that Paul may be outside the mainstream on this issue.

“I think there is an emerging consensus in the GOP that it needs to stand for basic civil liberties and civil rights as guaranteed by the Constitution,” the aide said.

But, tellingly, McConnell hasn’t yet commented on the NSA surveillance revelations, a clear indication the party position on the issue remains murky.

However, it’s unlikely Paul will temper his position on the issue, as he’d risk a base that’s growing increasingly skeptical of his commitment to libertarian causes.

Preston Bates, head of the libertarian Liberty for All super PAC, said libertarians are waiting to see what Paul will do next.

“Rand has done a great job using a bullhorn to raise awareness, but some of his supporters want to see how that education and engagement translates into action,” he said.

Many libertarians have pushed for the repeal of the PATRIOT Act entirely, a proposal that’s extremely unlikely to gain any traction in Congress. Paul’s bill to prevent similar NSA surveillance is also unlikely to go anywhere.

It’s unclear whether he’d be willing to stage another high-profile filibuster going forward, like the one that catapulted him to national prominence for his opposition to the administration’s use of drones. He met widespread support from both sides of the aisle for his filibuster, and was joined on the Senate floor by Sens. Rubio and Ted CruzRafael (Ted) Edward CruzTrump can save Republicans and restore sanity to California in 2018 Cruz says Cambridge Analytica assured him its practices were legal Dem battling Cruz in Texas: ‘I can understand how people think this is crazy’ MORE (R-Texas).

But where Cruz was supportive then, Bates warned that he could get out ahead of Paul on issues in the future and draw away libertarian support.

Cruz was one of the first voices to come out in favor of eliminating the Internal Revenue Service following the news that the agency had targeted conservative groups for extra scrutiny. Paul had advocated for abolishing the agency during his 2010 run for Senate, but took a more measured position this time, only issuing a resolution condemning its acts and calling for a full investigation into the situation.

Bates said he was surprised Cruz had been so outspoken in his opposition to the IRS, where Paul had seemed to moderate his views. And he suggested that, if Paul fails to take a hard-line stance on similar issues going forward, his base of support could splinter in 2016.

“He's gonna have to hope that there's no one more libertarian than him in the race,” he said of 2016.