Philip Reeker, the assistant secretary of State in the Bureau of Europe and Eurasian Affairs, is providing lawmakers with testimony that Secretary of State Mike Pompeo squashed a show of solidarity for Marie Yovanovitch, the former U.S. ambassador to Ukraine that President Trump removed after she opposed White House decisions, The Wall Street Journal reports. Reeker, who colleagues have told The Daily Beast is a straight shooter, is testifying behind closed doors on Capitol Hill on Saturday under subpoena in the impeachment inquiry—despite a White House direction for government officials not to cooperate with the inquiry.

Due to his position, Reeker has had a direct line to top state department officials, including Secretary Pompeo. “He is a career guy. He’s been at this a long time and he’s not about to give that all up to protect anyone,” one State Department official told The Daily Beast. A person familiar with his testimony tells the WSJ that Yovanovich “was a primary concern from his first week on the job.” Reeker was also reportedly present for a White House interagency meeting where a Department of Defense official raised concerns about Trump’s decision to hold military aid to Ukraine. His testimony is expected to provide critical detail to the alleged quid pro quo, adding fuel to the explosive testimony from William Taylor, acting U.S. ambassador to Ukraine, that came earlier this week.