“They’re not letting State Department lawyers in the room … they have not let State Department lawyers be part of these hearings,” Pompeo said. “That’s unheard of … I haven’t seen you all report that.”

As a member of the House during the Obama presidency, Pompeo served on the select committee investigating the 2011 consulate attack in Benghazi, Libya, and was a vocal critic of then-Secretary of State Hillary Clinton’s handling of that inquiry. Along with Rep. Jim Jordan (R-Ohio) he even issued his own addendum dissenting from the official findings of the Republican majority, complaining that the Obama administration had “stonewalled” the committee by refusing to turn over key documents or allowing crucial witnesses to testify.

In Friday’s interview, Pompeo said the House probe into the Benghazi attack treated Foggy Bottom more fairly, allowing State Department attorneys to listen to depositions and review transcripts of interviews after they were transcribed.

“This is deeply troubling to me,” Pompeo said, adding that the department has relayed these concerns to Democrats conducting the probe. “Because I have an obligation to protect the State Department. Not only [is it] classified information but private conversations that are confidential, are information we don’t want in the hands of others. And we’ve not been permitted to see what it is our former employees have told this committee.”

Pompeo’s criticisms echo the House Republicans’ strategy in dealing with the inquiry: He is rapping Democrats for the manner in which they are conducting their investigations, but not directly addressing the substance of the probe.

Reps. Jordan, Mark Meadows (R-N.C.), Lee Zeldin (R-N.Y.) and Matt Gaetz (R-Fla.) — some of the president’s top allies — have repeatedly complained about the private nature of the investigation. Gaetz and other Republicans have sought to attend impeachment hearings, even though they are not on the committees conducting the inquest. Kevin McCarthy, the House Republican leader, has pushed Speaker Nancy Pelosi to hold a vote to begin an impeachment probe, which would be largely ceremonial.

Rep. Adam Schiff (D-Calif.), chairman of the House Intelligence Committee, has made the State Department employees the star witnesses. Michael McKinley — a former top adviser to Pompeo who said he quit over Yovanovitch’s firing — gave a deposition this week, as did U.S. Ambassador to the EU Gordan Sondland, and George Kent, the deputy assistant secretary in charge of Ukraine. Yovanovitch appeared last week, and Kurt Volker, who recently resigned as special envoy to Ukraine, testified Wednesday.

Executive branch departments and agencies have uniformly rejected subpoenas and document requests from House Democrats. Nearly all of them — the State Department, the Pentagon, and the vice president’s office — have pointed to a letter signed by White House counsel Pat Cipollone last week calling the impeachment inquiry illegitimate and vowing not to cooperate.

The State Department has directed some current and former diplomats not to testify, but most of them have shown up for their depositions anyway. Democrats say it’s further proof that the White House impeachment blockade is crumbling.

Pompeo has largely brushed off questions about his involvement in the efforts of Giuliani, who claims he was acting at the behest of State Department diplomats. Sondland said this week that his understanding was that “all my actions involving Ukraine had the blessing of Secretary Pompeo,” who had even sent him “a congratulatory note that I was doing great work, and he encouraged me to keep banging away.”

Asked about current and former State Department employees who were choosing to testify in the probe, Pompeo seemed to encourage it — with a caveat.

“I hope they go to tell the truth,” he said. “And say things that are accurate to the best of their knowledge and complete — not only accurate, but complete and then I have every expectation that Congress will perform its oversight function properly if the process is appropriate … The American people ultimately hold their elected officials accountable. I believe deeply in the process. But you have to have a process that’s fair and reasonable.”

Andrew Desiderio and Kyle Cheney contributed to this report.