Executive Director of the McCain Institute Kurt Volker, President Trump's special envoy to Ukraine, has resigned, an Arizona State University official confirmed on Friday. He had been a U.S. special representative since 2017. The breaking news comes amid reports that Trump asked Ukrainian President Zelensky to interfere in U.S. elections and investigate Joe Biden, one of his top political rivals, in a phone call last July. The phone transcript released earlier this week did confirm that Trump asked the question, but showed no evidence of quid pro quo or that he had threatened to withhold military aid from Ukraine, as initially reported. In the whistleblower complaint that was released soon after, the whistleblower admits to having no "direct" knowledge of the call.

Still, Democrats concluded it was enough to announce an official impeachment inquiry against Trump, and are expected to question Volker all about it next week.

It doesn’t get more serious than this. It is a betrayal of his oath of office for President Trump to pressure a foreign country to interfere in our elections. And yet that is exactly what @realDonaldTrump did. #TruthExposed pic.twitter.com/MnB5ARJR35 — Nancy Pelosi (@SpeakerPelosi) September 27, 2019

Volker's name pops up in the whistleblower complaint about the phone call. According to the whistleblower, Volker helped organize meetings with Trump's personal lawyer Rudy Giuliani and Ukrainian officials.

Trump maintains that his phone call with Zelensky was "perfect" and that the Democrats' are inventing another scandal to try and boot him from office.

“IT WAS A PERFECT CONVERSATION WITH UKRAINE PRESIDENT!” — Donald J. Trump (@realDonaldTrump) September 27, 2019