U.S. Democratic lawmakers pursuing an impeachment inquiry of President Donald Trump are due to hear testimony on Wednesday from a former senior diplomat, who resigned his post last week as a top adviser to Secretary of State Mike Pompeo.
Michael McKinley is the latest diplomat set to provide closed-door testimony to lawmakers, who are examining whether Trump improperly pressured Ukraine to launch an investigation of former Democratic Vice President Joe Biden.
Biden is a top political rival and leading candidate for the Democratic 2020 presidential nomination.
The inquiry could lead to an impeachment vote in the Democratic-controlled House of Representatives, which would be followed by a trial in the Republican-controlled Senate.
So far few Senate Republicans have voiced criticism of Trump.
The House of Representative’s probe is focused on a July 25 phone call in which Trump pressed Ukrainian President Volodymyr Zelenskiy to investigate unsubstantiated allegations against Biden and his son Hunter Biden.
Democrats have accused Trump of pressuring a vulnerable U.S. ally to dig up dirt on a domestic rival after withholding 391 million dollars in U.S. security aid intended to help combat Russian-backed separatists in the eastern part of Ukraine.
Zelenskiy agreed to investigate. Trump eventually allowed the aid.
Trump has denied wrongdoing and defended his request to Zelenskiy. Biden and his son also deny wrongdoing.
McKinley, a diplomat who served as ambassador to Brazil and Afghanistan over his 37-year career, was not directly involved with Ukraine.
But he potentially could provide insight into State Department communications on the matter, as he served as an adviser to Pompeo from May 2018 until last week.
Pompeo, a close ally of Trump, has directed State Department employees not to cooperate with the inquiry, with limited success.
Career diplomat George Kent testified on Tuesday and former U.S. ambassador to Ukraine Marie Yovanovitch accused the Trump administration of recalling her in May based on false terms, in testimony last Friday.
Both received congressional subpoenas.
Gordon Sondland, a Trump political donor appointed as the U.S. ambassador to the EU, is expected to appear later this week in response to a subpoena after he initially declined to testify.
Others have remained defiant. Trump’s personal lawyer Rudy Giuliani and Vice President Mike Pence on Tuesday both refused to comply with subpoenas requesting documents related to the efforts to pressure Ukraine.
The Pentagon also said it could not share documents with lawmakers, citing “legal and practical concerns.” The White House budget office also faced a Tuesday deadline to respond.
Giuliani faces the possibility of being held in contempt of Congress by the House, but that penalty could be purely symbolic.
U.S. House Speaker Nancy Pelosi on Tuesday said she would not hold a full vote in the House right now to authorise the impeachment investigation.
The Democrat leading the probe, House intelligence panel chairman Adam Schiff, said the inquiry will likely include public hearings later.