Three U.S. House of Representatives committees are set to question Gordon Sondland, the U.S. ambassador to the European Union, on Tuesday to find out more about the interactions between President Donald Trump and Ukrainian officials.
The closed-door deposition is part of the ongoing impeachment inquiry in the House, which Trump on Monday again rejected as a "scam" perpetrated by Democrats who do not want him to win a second term in office next year.
Sondland has become a prominent figure in the probe because of his efforts to get Ukraine to commit to investigate Trump's potential presidential rival, former Vice President Joe Biden, and Biden's son, Hunter.
A whistleblower complaint that launched the impeachment inquiry says the day after Trump spoke by telephone with Ukraine President Volodymyr Zelenskiy, Sondland and U.S. envoy to Ukraine Kurt Volker met with the Ukrainian leader and other political figures.
The whistleblower said that according to readouts of those meetings recounted by U.S. officials, "Ambassadors Volker and Sondland reportedly provided advice to the Ukrainian leadership about how to 'navigate' the demands that the President had made of Mr. Zelenskiy."
Speaking to reporters Monday at the White House, Trump returned to his repeated defense of the conversation with Zelenskiy as a "perfect call." When asked if he is worried about what might emerge now that a second whistleblower has come forward, Trump replied, "Not at all."
He described the call as "congenial" and said there was "no pressure."
The House Intelligence, Foreign Affairs and Oversight committees have been leading the inquiry with depositions and subpoenas seeking documents from members of the Trump administration and the president's personal lawyer, Rudy Giuliani.
They issued fresh subpoenas Monday, demanding Defense Secretary Mark Esper, and Office and Budget and Management Acting Director Russell Vought turn over documents by Oct. 15 relating to Trump's decision to withhold military aid to Ukraine.
Part of the investigation includes examining whether or not Trump's decision to withhold military aid to Ukraine was tied to his request for a Ukrainian investigation into the Bidens.
No evidence of corruption by the Bidens in Ukraine has been found.