Representatives for the White House and the State Department could not be immediately reached to comment
President Donald Trump's administration on Tuesday blocked the US ambassador to the European Union from giving testimony in the House of Representatives' impeachment investigation of the Republican president.
Gordon Sondland, a Trump donor who started his diplomatic job in July, was due to meet behind closed doors with staff of three Democratic-led House committees Tuesday morning over the role he may have played in the president's efforts to get Ukraine to probe former Vice President Joe Biden, a political rival.
Sondland had apparently agreed to testify without a subpoena. Through his lawyer on Tuesday, he said he hoped "the issues raised by the State Department that preclude his testimony will be resolved promptly."
"He stands ready to testify on short notice, whenever he is permitted to appear," Sondland's lawyer, Robert Luskin, said in a statement.
Representatives for the White House and the State Department could not be immediately reached to comment.
The impeachment probe is focusing on a whistleblower's allegations that Trump used US military aid to secure a promise from Ukraine's president to investigate Biden, a leading candidate for the 2020 Democratic presidential nomination, and his son Hunter, who was on the board of a Ukrainian energy firm.
Sondland was a key witness for the House Foreign Affairs, Intelligence and Oversight Committees, whose staff had been expected to ask him why he became involved in dealings with Ukraine, which is not a member of the EU.
Trump has derided the impeachment inquiry and denied he did anything wrong in a July 25 phone call with Ukrainian President Volodymyr Zelenskiy in which Trump pushed for an investigation of Biden and his son.
"I would love to send Ambassador Sondland, a really good man and great American, to testify, but unfortunately he would be testifying before a totally compromised kangaroo court, where Republicans' rights have been taken away, and true facts are not allowed out for the public to see," Trump wrote on Twitter.
According to text messages released by House committee leaders last week, Sondland was heavily involved in contacts with Zelenskiy as he sought a meeting with Trump, and Ukrainian officials expressed concern at the administration's decision to block nearly $400 million in US military assistance for Kiev.
In one of the texts, for example, Sondland emphasized that Trump "really wants the deliverable."
Representative Adam Schiff, the Democratic chairman of the House intelligence committee, which is spearheading the impeachment probe, said the State Department was withholding messages from Sondland that are relevant to the inquiry.
Schiff told reporters the failure to allow Sondland to testify and turn over his text messages or emails was further evidence of obstruction.
Following the allegations that Trump pressured Zelenskiy to investigate Biden while withholding the military aid, House Speaker Nancy Pelosi announced a formal impeachment investigation last month.
Concerns about the July 25 call, and possible Trump threats to Ukraine, came to the attention of Congress in a report by a whistleblower. On Sunday, lawyers said a second whistleblower had come forward to substantiate that complaint.
The request for Sondland's appearance marked a shift for the investigation because he is a political appointee. Previous witnesses have been career officials, including the former US special envoy for Ukraine, Kurt Volker, and Michael Atkinson, the inspector general of the US Intelligence Community.
Sondland was a Seattle-based hotelier who donated $1 million to Trump's inauguration committee. He was nominated by Trump to his position as ambassador in May and confirmed by the US Senate in June. He presented his credentials at the European Commission in July.
Another career diplomat, Marie Yovanovitch, is scheduled to meet with the committees behind closed doors on Friday. Yovanovitch was the US ambassador to Ukraine until Trump recalled her in May before her term was up, after the president's supporters questioned her loyalty.
The impeachment inquiry has heightened bitter partisan divisions in Congress. Trump's fellow Republicans control the Senate where a trial on whether to oust the president would be held if the House ultimately votes to impeach him.
Trump has reacted furiously to the inquiry, using obscenities and insulting nicknames for Democratic lawmakers in posts on Twitter. Administration officials, and some of their Republican allies in Congress, have questioned whether they have any obligation to cooperate with the inquiry.
The White House was expected to tell Pelosi this week that it would ignore lawmakers' demands for documents until the House holds a vote to approve the impeachment inquiry.
Pelosi says a vote is not needed, although Democrats say the House would back the inquiry if there were a vote.