US special representative on Ukraine Kurt Volker resigned after Congress ordered him to speak in an impeachment investigation on President Donald Trump, news agency PTI quoted a source as saying. A person familiar with the matter who requested anonymity confirmed Volker's resignation Friday, which was first reported by the student newspaper at Arizona State University, where he directs an institute.
Donald Trump has come the closest to being impeached after US Democrats opened a formal inquiry into allegations that he sought help from a foreign power - Ukraine - to damage a political rival. House Speaker Nancy Pelosi announced the formal impeachment inquiry into Trump saying said the president "must be held accountable". Trump has denied any impropriety and called the efforts "breaking news Witch Hunt garbage".
However, Donald Trump is unlikely to face impeachment as the inquiry is unlikely to pass the Senate, where Republican Party has a clear majority.
Many Democrats have been calling for an impeachment inquiry into Trump even before the latest 'Ukraine' controversy. The row was sparked after reports surfaced saying that an intelligence whistleblower had lodged a formal complaint about a phone call between Trump and Ukraine President Volodymyr Zelensky.
It is be alleged that during the conversation Trump threatened to withhold military aid to force Ukraine to investigate corruption allegations against former Vice-President Joe Biden and his son Hunter.
Biden is currently the front-runner in the race for Democratic nominee for 2020 Presidential Elections.
Trump has already acknowledged discussing Joe Biden with Zelensky but said he was only trying to get Europe to step up assistance by threatening to withhold military aid.
Nancy Pelosi has been resisting the call to launch an impeachment inquiry so far. However, she finally made the call and said Trump had committed "a violation of the law", She called his actions "a breach of his constitutional responsibilities".