Jennifer Williams, special adviser for Europe and Russia in the Office of U.S. Vice President Mike Pence

Jennifer Williams, a foreign policy aide to US Vice President Mike Pence has slammed as ‘inappropriate the phone call between U.S. President Donald Trump and his Ukrainian counterpart, according to a transcript released on Saturday.

The call is at the centre of Congress’ impeachment investigation.

Williams who was listening to the call on July 25, testified that Trump’s insistence that Ukraine carry out politically sensitive investigations “struck me as unusual and inappropriate.”

She said the discussion was “more political in nature” than phone calls with other foreign leaders, and included what she viewed as specific references to the president’s “personal political agenda.”

Trump’s call is at the heart of the Democratic-led inquiry into whether the Republican president misused U.S. foreign policy to undermine former Vice President Joe Biden, one of his potential opponents in the 2020 election.

The House of Representatives on Saturday also released a transcript of an earlier closed-door deposition by Tim Morrison, a former White House aide with the National Security Council focusing on Europe and Russia policy, who was also on the call.

Morrison, who resigned a day before his deposition last month, and Williams both expressed concerns about Trump’s remarks to Ukrainian President Volodymyr Zelenskiy. Williams and Morrison are scheduled to testify publicly next week.

“I was not comfortable with any idea that President Zelenskiy should allow himself to be involved in our politics,” Morrison told lawmakers. He also said he found Zelenskiy’s tone in the call with Trump to be “obsequious.”

Morrison declined to say he thought the call was illegal or improper, stressing instead that he thought it would leak, damaging relations with Ukraine. He said he only learned later that the aid to Ukraine was conditioned on the investigations.

In the first public hearing last week, acting ambassador to Ukraine William Taylor pointed to Trump’s keen interest in getting the eastern European ally to investigate Biden and reiterated his understanding that $391 million in U.S. security aid was withheld from Kiev unless it cooperated.

Morrison said he had reviewed Taylor’s testimony and did not dispute it on any significant points.

House investigators on Saturday also heard closed-door testimony from a White House budget official about the holdup of military aid to Ukraine. Mark Sandy, a career official of the Office of Management and Budget, was the first person from OMB to testify before the inquiry after three political appointees defied congressional subpoenas to appear.

Sandy spoke about how unusual it was to have a political appointee come in and place a hold on military aid to Ukraine, CNN quoted a source familiar with the testimony as saying.

Democratic Representative Jamie Raskin, a member of the Judiciary and Oversight Committees, said Sandy was brought in to shed light on whether military aid was held up for political reasons.