WASHINGTON – Mike Dubke has resigned as White House communications director, a senior administration official confirmed Tuesday, in the first of what could be a series of changes to President Trump’s senior staff amid the growing Russia scandal.

Dubke, who served in the post for three months, tendered his resignation May 18. He offered to stay on to help manage communications in Washington during Trump’s foreign trip, and the president accepted.

Dubke’s last day on the job has not been determined, but it could be Tuesday. He is expected to be at the White House on Tuesday to meet with his staff, said the official, who required anonymity to discuss a personnel move that has not yet been formally announced.

Dubke’s resignation was first reported by Mike Allen of Axios in his Tuesday morning newsletter.

Dubke, who has worked closely with White House press secretary Sean Spicer, served as a behind-the-scenes player helping manage communications strategy, responses to crises such as the firing of James Comey as FBI director, as well as rollout plans for policy and other initiatives.

The communications operation – and Dubke and Spicer specifically – have come under sharp criticism from Trump and many senior officials in the West Wing, who believe the president has been poorly served by his staff, in particular in the aftermath of the Comey firing.

Dubke was the rare Trump newcomer in a White House in which personal relationships and proximity to the president is the currency. He arrived in mid-February, a few weeks into Trump’s term, and struggled to build alliances with some colleagues on the senior staff, not having worked on Trump’s campaign or his transition team.

Jason Miller, the Trump campaign’s senior communications adviser, was slated to serve as communications director in the White House, but he stepped aside a few weeks before Inauguration Day, saying he wanted to spend more time with his family.

During the first few weeks of the presidency, Spicer held the dual roles of press secretary and communications director, but it became too much for him. Dubke was then hired to fulfill the communications director responsibilities.

Dubke previously was a Republican strategist who founded Crossroads Media and had long ties to party establishment figures, including strategist Karl Rove.