Jim Murphy said Thursday that he has taken "a step back" from his role as Donald Trump's national political director.
"I have not resigned but for personal reasons have had to take a step back from the campaign," Murphy told Politico in a statement.
Murphy, who was hired by the Republican nominee's campaign in June, was a senior adviser during Kansas Sen. Bob Dole's White House runs in 1988 and 1996.
He also was floor operations manager at three Republican conventions.
A longtime Washington lobbyist, Murphy has played a critical role in organizing field operations in battleground states, Politico reports. His departure comes fewer than three weeks before Election Day.
He is a close ally of Paul Manafort, Trump's former campaign chairman, who resigned in August.
Murphy was hired after the Trump campaign fired Rick Wiley, who had been in the post for about two months.
The Trump campaign has not commented on Murphy's decision.