Tim Morrison, the National Security Council's Russia and Europe director has left his White House post as his Thursday impeachment inquiry testimony looms.

Where it stands: Morrison told the House committees Thursday morning that he resigned on his volition late Wednesday evening, two sources familiar with the matter tell Axios.

Morrison said his decision was not influenced by the impeachment investigation, but one of the sources said “whether you choose to believe that is up to you.”

Barbara Van Gelder, Morrison's lawyer, told Axios' Alayna Treene she had "no comment" when asked about NPR's report

Why it matters: Morrison is scheduled to testify before House impeachment committees on Thursday. Lt. Col. Alexander Vindman testified Tuesday that the White House memo of President Trump's July 25 phone call with the Ukrainian president "omitted crucial words and phrases." Vindman said he provided written edits and corrections of the memo to Morrison, per the New York Times.

Vindman added that "some of his edits appeared to have been successful," aside from two involving Burisma — the Ukrainian company in which Hunter Biden served on the board in 2014 — and former Vice President Joe Biden.

Go deeper ... Impeachment inquiry: What to watch in the week ahead