U.S. President Donald Trump`s special representative for Ukraine, Kurt Volker, resigned on Friday, sources familiar with the situation said.
A whistleblower complaint from within the intelligence community, released publicly on Thursday, described Volker as trying to "contain the damage" from efforts by Trump`s lawyer Rudy Giuliani to press Ukraine to investigate Democrats.
Volker, who had served in the position on a part-time, unpaid basis since 2017, had sought to help Ukraine`s government resolve its confrontation with Russia-sponsored separatists.
The State Department did not immediately respond to a request for comment.
Democrats in the U.S. House of Representatives, who are conducting an impeachment investigation of Trump, have sought testimony from Volker relating to a July 25 phone call in which Trump encouraged Ukraine`s president to investigate Joe Biden, a political rival.
Volker`s resignation was first reported by the State Press, a student-run publication at Arizona State University, which backs a think tank where Volker serves as executive director.