The phone call between US President Donald Trump and his Ukrainian counterpart at the center of Congress’ impeachment investigation was “inappropriate,” a foreign policy aide to Vice President Mike Pence told lawmakers, according to a transcript released on Saturday.

Jennifer 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.”

As did Williams, Morrison told lawmakers he had concerns about Trump’s remarks to Ukrainian President Volodymyr Zelenskiy. Williams and Morrison are scheduled to testify publicly next week.

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

Morrison declined to say he thought the call was illegal or improper, stressing instead that he thought it would leak, and damage relations with Ukraine.

In a disclosure that drew the most attention 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 US security aid was withheld from Kiev unless it cooperated.

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, is the first person from OMB to testify before the inquiry after three political appointees defied congressional subpoenas to appear.

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.

“This is a technical part of our investigation,” Raskin told reporters outside the interview room. “We want to know exactly how the president translated his political objective to shake down the Ukrainian government for the favors he wanted the budget process.”

Trump defended his attack on Yovanovitch, saying he had the right to free speech.Yovanovitch, a career diplomat, testified on the second day of televised impeachment hearings, which will resume next week.

While Yovanovitch’s testimony dominated headlines on Friday, a closed-door deposition lawmakers held later in the day with David Holmes, a US embassy official in Kiev, could prove more consequential.

Holmes told lawmakers he overheard a phone call between Trump and Gordon Sondland, the US ambassador to the European Union, in which the president inquired about Ukraine’s willingness to carry out investigations of Biden and his son.