Volker's resignation was broken by the State Press, the student-run newspaper at Arizona State University. Volker acts as the executive director of the McCain Institute, which is a think tank associated with the university.
— The State Press (@statepress) September 27, 2019
Although an ASU official did confirm Volker's resignation Friday, they did not specify whether or not the US envoy would continue working with the university's institute. The ASU official also confirmed that Volker met with US Secretary of State Mike Pompeo Friday to announce his resignation.
— Donald J. Trump (@realDonaldTrump) September 27, 2019
The whistleblower complaint released Thursday alleges that Volker coordinated meetings with Trump's lawyer Rudy Giuliani and Ukrainian officials. The complaint also states that Volker allegedly went to Kiev, the capital of Ukraine, to advise Ukrainian officials on how to fulfill Trump's requests.
According to Reuters, Democrats in the US House of Representatives are seeking testimony from Volker regarding his alleged actions.
US House Speaker Nancy Pelosi announced a formal impeachment inquiry against Trump earlier this week after Trump and Zelensky's July 25 call was revealed to be at the center of an August whistleblower report that the Trump administration fought to keep from Congress.
Pelosi has accused Trump of seeking Ukraine's help to investigate the case against US 2020 presidential candidate and former Vice President Joe Biden, who publicly admitted in 2016 to having threatened Ukrainian authorities with withholding $1 billion in US loan guarantees if Kiev did not fire the prosecutor who had been investigating a Ukrainian gas company connected to Biden's son.
House Democrats are also claiming that Trump threatened to withhold military aid to Ukraine unless Zelensky looked into the Biden case.
— Donald J. Trump (@realDonaldTrump) September 24, 2019
Pelosi's announcement came on the heels of Trump stating that he would allow for the release of the transcripts of the phone conversation between Zelensky and himself.
In the phone call with Zelensky, Trump said: "There's a lot of talk about Biden's son, that Biden stopped the prosecution, and a lot of people want to find out about that, so whatever you can do with the attorney general would be great. Biden went around bragging that he stopped the prosecution, so if you can look into it ... it sounds horrible to me."
This latest development comes amid news that the US House Intelligence Committee will return from recess for a closed hearing on 4 October. The panel is expected to hear from Michael Atkinson, the intelligence community inspector general who handled the whistleblower complaint.
