Trump's communications director will be latest to leave the White House

— -- The resignation of the White House communications director is the latest staff change in the first four months of the Trump administration.

Mike Dubke resigned on May 18 but offered to stay until the end of the president's first foreign trip, which wrapped up this past weekend.

Dubke was not part of the team that traveled abroad with President Donald Trump, and as of today is still on the job. His last day has not yet been set.

Sources told ABC News that on May 15, three days before he resigned, Dubke, along with press secretary Sean Spicer and principal deputy press secretary Sarah Huckabee Sanders, met with President Trump.

The president made it clear that Spicer's and Dubke’s jobs were on the line, the sources said.

Trump was “frustrated across the board” with his communications team, especially over anonymous leaks to the media, the sources said.

Latest to leave

Trump senior adviser Kellyanne Conway suggested on "Fox & Friends" this morning that it was Dubke's decision to leave.

"People in administrations tend to leave on their own volition as well. They tend to find that working 18-hour days in different environments are maybe what's not best suited for them," Conway said.

Conway said Dubke "has expressed his desire to leave the White House and made very clear that he would see through the president's international trip."

White House chief of staff Reince Priebus said in a statement Monday, "Mike tendered his resignation just before the president's historic international trip and offered to remain on board until a transition is concluded. Mike will assist with the transition and be a strong advocate for the president and the president's policies moving forward."

Deputy Chief of Staff Katie Walsh left the White House in March and, according to two sources with direct knowledge, Walsh will be consulting for an outside group that aims to help with Trump’s agenda.

National Security Adviser Michael Flynn was fired in February after mischaracterizing his conversations with the Russian ambassador to the United States, Sergey Kislyak.

It was announced May 19 that former Deputy National Security Adviser K.T. McFarland, who previously worked under Flynn, was leaving her role because Trump was nominating her as U.S. ambassador to Singapore.

Beyond that, Trump fired FBI Director James Comey earlier this month.

Earlier, in late January, the president fired then-acting Attorney General Sally Yates after she instructed the Department of Justice not to defend Trump's Jan. 27 executive order temporarily barring entry to the U.S. of people from seven predominantly Muslim countries. That executive order was later blocked by federal judges and replaced by a subsequent executive order that is itself now tied up in the courts.

Spicer takes the podium

One familiar face who was not very visible during the foreign trip was Spicer.

The press secretary along with others from the administration accompanied the president on the trip to the Middle East and Europe, but he was not among those who gave any on-camera briefings during the week-long trip.

And in the days leading up to the trip, Spicer spoke to members of the press during off-camera gaggles rather than in more formal briefings.

Spicer is slated to be back on camera today, however, in what will be his first briefing from the White House press room in 15 days.

ABC News' Jonathan Karl, John Santucci and Katherine Faulders contributed to this report.