A longtime US diplomat who served as President Donald Trump’s special envoy for Ukraine will tell his story to congressional committee staff on Thursday as part of a Democratic-led impeachment probe of the Republican president. Kurt Volker resigned as special representative for Ukraine negotiations on Friday, the day after the public release of a whistleblower complaint that described him as trying to “contain the damage” from efforts by Trump’s lawyer Rudy Giuliani to press Ukraine to investigate Democrats. Volker’s meeting with the committee comes after an emotional day in the impeachment inquiry on Wednesday, when Trump railed at journalists during a news conference, resorted to the use of an expletive on Twitter and called the probe “a hoax and a fraud” while pledging to cooperate. Democratic lawmakers had said earlier on Wednesday they were prepared to subpoena White House records about Trump’s July 25 telephone call with Ukrainian President Volodymyr Zelenskiy. Charges that Trump pressured Zelenskiy in that call to investigate former Vice President Joe Biden, a leading rival in Trump’s bid for re-election in 2020, helped prompt House of Representatives Speaker Nancy Pelosi to announce a formal impeachment investigation last week. On Thursday, staff from the House Foreign Affairs, Intelligence and Oversight committees will conduct a transcribed interview with Volker. The 54-year-old, who is also a former US ambassador to NATO, is appearing voluntarily. The briefing will take place behind closed doors, the first of a series of events in the probe, none of them public, scheduled within the 10 days. More are expected. Late on Wednesday, US Representative Mike McCaul, the top Republican on the House Foreign Affairs Committee, criticized the session with Volker, saying that Foreign Affairs Committee Republicans were not being given equal representation or the chance to question Volker. He also expressed concern that US Representative Eliot Engel, the Democratic House foreign affairs chairman, had ceded oversight of US foreign policy to the Intelligence Committee because that panel, he said, would lead the questioning of Volker. An Intelligence Committee aide said the panel’s staff would conduct the interview because Pelosi had designated it as the lead committee in the impeachment inquiry. Intelligence Committee investigators have been working with the Foreign Affairs and Oversight committees, “both of which will have equal Majority and Minority representation,” the aide said in an email. Representatives for the Foreign Affairs Committee did not immediately respond to a request for comment. On Friday, Intelligence Community Inspector General Michael Atkinson will testify at an Intelligence Committee hearing. Marie Yovanovitch, who was the US ambassador in Kiev until Trump recalled her in May before her normal term was up, will meet with committee staff on Oct. 11. ‘Perfect’ – Or Wrong? Trump has denied wrongdoing, repeatedly calling his call with Zelenskiy “perfect.” Pelosi dismissed that characterization at a news conference on Wednesday, saying: “It’s not perfect – it’s wrong.” Some of Trump’s Republican allies have joined him in seeking to discredit Representative Adam Schiff, chairman of the House intelligence panel, after a New York Times report on Wednesday that the whistleblower had contacted the committee for advice on how to proceed. Both Republicans and Democrats familiar with the process said, however, that Schiff’s panel had acted properly in advising the person to contact an Inspector General and seek legal counsel. Staff from eight Senate and House congressional committees, including Republicans and Democrats, also reacted with surprise on Wednesday after a briefing by the State Department’s inspector general, Steve Linick.