Jennifer Williams, an aide to US Vice President Mike Pence, arrives in Congress to testify in the impeachment inquiry against President Donald Trump (ANDREW CABALLERO-REYNOLDS)

Washington (AFP) – A national security aide to Vice President Mike Pence arrived in Congress Thursday to testify in the impeachment inquiry against President Donald Trump as momentum in the investigation picked up ahead of next week’s open hearings.

Jennifer Williams listened to Trump’s controversial July 25 phone call with Ukraine leader Volodymyr Zelensky, and could either support or dampen allegations that Trump abused his powers by pressuring Zelensky to investigate Trump’s possible 2020 election rival.

Democrats allege that Trump held up $391 million in military aid for Ukraine to force Zelensky to find dirt on Democrat Joe Biden, and also to find evidence supporting a widely discredited theory that Ukraine helped Democrats in the 2016 election.

A veteran diplomat who advises Pence on Europe and Russia, Williams will be the first person from the vice president’s office to testify.

“We expect her testimony will largely reflect what is already in the public record,” her lawyer Justin Shur said in a statement to US media.

Trump has defended the July call as “perfect” despite a heavily edited transcript appearing to support the allegations against him.

The call record shows Trump asked Zelensky for a “favor” and specified that Ukraine should open investigations into Biden, as well as into the unsupported tale that  Ukraine helped the Democrats in 2016.

That closely matched the claims of an intelligence community whistleblower, whose anonymous August complaint that Trump’s actions in the call were improper sparked the impeachment probe.

Statements and newly released transcripts from the closed-door testimony of other White House and State Department witnesses back up the allegations that Trump illicitly sought a foreign country’s help for his reelection campaign next year.

Those allegations form the core of the impeachment inquiry, which will begin open hearings next Wednesday.

Trump continued to defend his Ukraine work Thursday, tweeting that people should “Read the Transcript” of the call.

He also defended himself against a Washington Post story that said he had asked Attorney General Bill Barr to come out in public and state that he did nothing wrong in the call with Zelensky.

Barr made no such statement, although the Justice Department decided in August that the whistleblower’s complaint did not merit investigation.

“Bill Barr did not decline my request to talk about Ukraine. The story was a Fake Washington Post con job with an ‘anonymous’ source that doesn’t exist,” Trump tweeted.

Disclaimer: Validity of the above story is for 7 Days from original date of publishing. Source: AFP.