Republicans were outraged when they learned that the Obama administration had “unmasked”—revealed the real names of—Trump associates who were caught in the surveillance of foreign officials.

The National Security Agency, the eavesdropping arm of the U.S. intelligence community, indicated over a year ago it would give Republicans in Congress more visibility into who gets unmasked and why, according to members of Congress. But so far, multiple congressional Republicans familiar with the situation say, NSA hasn’t sufficiently delivered. Their frustration with the NSA is close to boiling over.

Years-long conversations between House Intelligence Committee Republicans and the NSA regarding the topic haven’t produced satisfactory change, those members of Congress say. The frustration is percolating in the background as members of the intelligence community have been roving the Hill for closed-door, classified meetings and hearings about their new budget.

Rep. Mike Conaway, a Texas Republican on the Intelligence Committee, told The Daily Beast that Republicans aren’t satisfied with the agency.

“We’ll continue to demand that they build the systems in place to allow a more timely oversight,” he said. “We’ll continue to demand that they do it.”

Members said representatives of the agency indicated more than a year ago that they would give the House Intelligence Committee more visibility into their unmasking decisions—but still haven’t delivered.

“There’s continued frustration there,” one House Republican told The Daily Beast.

The controversy over unmasking burst into view in early 2017. On March 4, 2017, at 6:35 a.m., President Trump fired off a tweet that became one of his most famous:

In the weeks after the president fired off that that missive, news broke that Susan Rice—national security adviser for the final years of the Obama administration—asked to see the identities of Americans mentioned in intelligence reports about Russian efforts to interfere in the 2016 election and court officials in Trumpworld.

In intelligence reports, the names of Americans are “masked” to protect their privacy. But some officials can have those names revealed, or “unmasked,” in some circumstances. And that’s what Rice did, revealing the names of Trump associates. Republicans have long argued that she asked to see their names in hopes of using the information to inflict political damage on Trumpworld. Democrats, meanwhile, say Rice did nothing wrong.

The issue was one of many flashpoints during the committee’s investigation of Russian interference in the 2016 race. Under the auspices of then-Chairman Devin Nunes, the committee started an investigation of the interference that quickly morphed to include an investigation of the investigators who identified the interference. After making a curious late-night trip to the White House, Nunes stepped back from overseeing the probe—which practically became two separate projects.

In the months that followed, committee members interviewed scores of people for their investigation, including two sitting members of Congress. They released a memo on the secret court that authorizes surveillance of Americans (drawing scorching criticisms from Democrats and the intelligence community), and some of their findings found their way to a lawyer for longtime Trump lawyer Michael Cohen. The final report the committee majority released—with censure from Democrats—knocked the intelligence community for assessing that the Kremlin wanted Trump to win. Special Counsel Robert Mueller’s report, which came out earlier this year, sided with the intelligence community on that point.

After Democrats took control of the House last November, new committee Chairman Adam Schiff re-opened the Russia probe, bringing on new staff with expertise in federal investigations and financial crimes. Losing the majority means Republicans have lost leverage over the NSA. But they haven’t lost interest—even a little bit.

Committee Republicans have discussed multiple ways of expanding their oversight of the unmasking process, according to one Republican member of Congress familiar with the talks. One potential change would have the agency send a report to the committee every few months naming which Americans were unmasked, which intelligence officials had their names revealed, and why.

“We think these reforms are important,” the member said.

Officials in the NSA, meanwhile, have expressed concern that potential pitches would result in additional scrutiny of career intelligence officials but not of political appointees, according to the member, adding that the topic has come up in hearings with intelligence community officials, as well as in talks between committee staff and legislative affairs staff representing the spy agency. Spokespersons for the NSA and the Office of the Director of National Intelligence declined to comment.

Meanwhile, a Democratic official on the committee said the Republican proposal detailed to The Daily Beast might be illegal.

“Any proposal to disseminate bulk, unminimized U.S. person identity information contained in NSA reporting directly to Congress, without any specific justification as to the need to know the information about each U.S. person and on a quarterly basis, would be potentially unlawful and violative of the privacy that Republicans ostensibly seek to protect,” the official said.

The official also called Republican criticism of the Obama administration’s unmasking procedures a “conspiracy theory.” The issue is one of many that has fueled partisan sniping on the House panel.

“From what I can tell, the argument about unmasking has been used as a political ploy to deflect from other transgressions of the Trump administration,” said one congressional Democrat familiar with the controversy. “As far as I can tell, Republicans have not been able to definitively show that there was a breakdown in the process in terms of what happened in respect to any of this stuff.”

The fact that Republican frustration with the NSA persists—and that the agency has not voluntarily met members’ demands for more visibility into its workings—points to the legs of the controversy. And while some Democrats say Republican criticism of the agency is just an effort to run interference for Trump, that isn’t a consensus view in the intelligence community.

“I take quite seriously the risks that there would be a politically inspired unmasking and I think that it’s appropriate to have controls and oversight in that area,” said Stewart Baker, former general counsel to the NSA. “I thought Nunes was right to raise it and right to look at it, and that it was fair to impose the oversight that was imposed by law.”

At the same time, Baker cautioned that the one potential solution described to The Daily Beast could actually make matters worse, from a privacy perspective.

“If you’re worried about the political consequences of unmasking somebody to high levels in the executive branch, it’s not clear that you’ve cured that problem by also unmasking them to a whole bunch of political actors on the Hill,” he said.