The US special envoy to Ukraine resigned from his post Friday, a day after his name surfaced in the White House whistleblower complaint as a liaison between President Trump and the government of Ukrainian President Volodymyr Zelensky, a report said.

Kurt Volker met with Secretary of State Mike Pompeo to tender his resignation, the Arizona State Press reported.

According to the whistleblower complaint, Volker and Gordon Sondland, the US ambassador to the European Union, tried to advise the Ukrainian government on how to navigate demands that Trump and his personal lawyer, Rudy Giuliani, made regarding a potential investigation into the son of Democratic presidential contender Joe Biden.

Democrats are moving forward with impeachment proceedings against Trump, alleging he illegally used his office to pressure Ukraine to dig dirt on a political rival.

Trump has denied wrongdoing and has complained the White House source who gave the whistleblower information is a “spy.”

CNN confirmed Volker’s resignation, which was first reported by the Phoenix-based school newspaper. Volker is executive director of the McCain Institute, a Washington, DC, think tank that is run in cooperation with Arizona State.