Secretary of State Mike Pompeo has accused House Democrats of attempting to “intimidate, bully, and treat improperly” State Department officials who have been subpoenaed to testify as part of the impeachment inquiry into President Trump and says they will not show up. “I am concerned with aspects of your request… that can be understood only as an attempt to intimidate, bully, and treat improperly the distinguished professionals of the Department of State, including several career Foreign Service Officers, whom the committee is now targeting,” Pompeo wrote to House Foreign Affairs Committee Chairman Eliot Engel (D-NY) on Tuesday. “Therefore, the five officials subject to your letter may not attend any interview or deposition without counsel from the Executive Branch present to ensure that the Executive Branch’s constitutional authority to control the disclosure of confidential information, including deliberative matters and diplomatic communications, is not impaired.”

The House Foreign Affairs, Intelligence, and Oversight committees have requested depositions from five current and former State Department officials regarding their knowledge of the Trump-Ukraine phone call. The officials include former Ambassador to Ukraine Marie “Masha” Yovanovitch and Kurt Volker, a Ukrainian envoy who resigned last week after Rudy Giuliani implicated him in the scandal. The interviews have been scheduled to take place over the next two weeks, starting Wednesday. The chairmen have also subpoenaed Pompeo to produce documents related to Trump’s interactions with Ukraine, giving him an Oct. 4 deadline to hand them over.

Later Tuesday, Engel—along with House Intel Chair Adam Schiff (D-CA) and House Oversight Chair Elijah Cummings (D-MD)—said in a statement that Pompeo was a “fact witness in the House impeachment inquiry” if he actually listened in on Trump’s July 25 phone call with the Ukrainian president. “He should immediately cease intimidating Department witnesses in order to protect himself and the President,” the statement read.