This story first published November 5 ahead of Jennifer Williams' closed-door deposition. It has been updated with additional developments after her initial testimony.

Washington (CNN) A senior adviser to Vice President Mike Pence who complied with a request to testify earlier this month in front of the committee leading the impeachment inquiry was disparaged by President Donald Trump on Sunday, two days before she is set to testify publicly before the panel.

Jennifer Williams, who was the first person on Pence's national security team to appear, and knowledge of how much the vice president knew about the efforts by Trump and those around him to push Ukraine to launch investigations into Joe Biden and his son, as well as 2016 election interference.

During a closed-door deposition earlier this month, Williams told lawmakers she had been in the White House Situation Room listening to Trump's July 25 phone call with Ukrainian President Volodymyr Zelensky in real time and reviewed a transcript of Trump's April call with Zelensky prior to Pence's own April call with the then-Ukrainian President-elect. Williams also listened to a second call between Pence and Zelensky, which took place on September 18 after a US hold on security assistance to the country had been lifted. She testified that Trump's request for specific investigations struck her as "unusual and inappropriate" and "shed some light on possible other motivations" for his decision to freeze security aid to Ukraine.

Tweeting a day after Williams' earlier, closed-door testimony was released, Trump resurfaced an unfounded accusation he has raised against other officials who have testified in the probe, characterizing Williams as a Never Trumper and associating her with other "Never Trumpers." The President also urged Williams to "read BOTH transcripts of the presidential calls."

Pence's office on Sunday declined to defend Williams after Trump's Twitter attack, with Pence's press secretary Katie Waldman simply telling CNN: "Jennifer is a State Department employee."

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