Lt. Col. Alexander Vindman, one of the key witnesses at the House impeachment hearings against President Donald Trump, is expected to be on his way out of the National Security Council soon, according to multiple reports.
CNN reports Vindman was supposed to stay until July, but his departure could come as soon as this month.
It's not clear if the departure is of his own choosing or a decision by the White House. Bloomberg News cites sources who say the White House will portray it as an effort to downsize the NSC and not as retribution for Vindman's testimony.
Vindman was among the officials who listened in to the July 25 call when Trump asked Ukrainian President Volodymyr Zelenskiy for “a favor” -- investigations of Democrat Joe Biden and other issues.
“It was inappropriate, it was improper for the president to request, to demand an investigation into a political opponent,” Vindman told the House Intelligence Committee last November.
RELATED: VERIFY: Claim that senators who voted guilty in impeachment represent more Americans is misleading
Trump has been upset about Vindman ever since he testified, sources tell CNN, and some of his duties were cut back.
Some of Trump's supporters criticized Vindman -- a 20-year military officer who received a Purple Heart for being wounded in the Iraq War -- for testifying.
Jennifer Williams, who testified alongside Vindman, has also reportedly left her post two months early as an adviser to Vice President Mike Pence on Europe and Russia.
The Associated Press contributed to this report.