Donald Trump's director of communications, Mike Dubke, has resigned without explanation after just three months in the role.
The PR chief reportedly offered to stay on until the end of the US President's first foreign visit to ensure a smooth transition.
The 47-year-old arrived in mid-February after Mr Trump had already taken office, and had not previously worked on his campaign or transition.
It was unclear why Mr Dubke decided to step down but insiders claimed he failed to "gel" with Mr Trump's staff, Axios reports.
Mr Dubke wrote in a statement that it had been an honour to serve Mr Trump and "my distinct pleasure to work side by side, day by day with the staff of the communications and press departments."
White House counsellor Kellyanne Conway said he handed in his resignation before Mr Trump left earlier this month.
Ms Conway told Fox News Mr Dubke "made very clear that he would see through the President's international trip, and come to work every day and work hard even through that trip because there was much to do here back at the White House."
The former GOP strategist had been brought in to help shape the Republican leader's messaging. However, Mr Trump has reportedly become increasingly frustrated with his "leaky" communications team since taking office, and some senior insiders in the West Wing believe he has been poorly served by his staff, according to the Washington Post.
Mr Dubke's departure could offer an opportunity for a wider shake-up within the former real estate mogul's top team.
It follows reports Mr Trump was considering replacing staff with producers from television channel Fox News.
He was also reportedly considering replacing White House press secretary Sean Spicer with Fox News' “The Five” co-host Kimberly Guilfoyle, according to The New York Times.
Rumours of discontent began circling after Mr Trump kept his communications team in the dark about the firing of FBI Director James Comey. The team were forced to explain the decision with just an hour's notice and no real discussion with Mr Trump himself.
