John Kelly, the White House chief of staff, has been interviewed by special counsel Robert Mueller’s team and is expected to quit in the coming days, CNN reported on Friday.

Kelly “responded to a narrow set of questions” in recent months related to potential obstruction of justice, the TV network said, citing three sources. This was after White House lawyers initially objected to Mueller’s request to do the interview earlier in the summer.

Most of Mueller’s other interviewees were part of the Trump election campaign or presidential transition. Kelly, however, only became chief of staff in July last year.

At the time it was hoped he would steady the ship – and curb Donald Trump’s Twitter habit – after the turbulence of Reince Priebus’s tenure. But the strained relationship between the president and Kelly, 68, a retired Marine Corps general and former homeland security secretary, has been widely chronicled.

According to CNN, it is now so bad that the pair are not on speaking terms.

This is far from the first time Kelly has been rumoured to be on the brink. In October last year he made an extraordinary appearance in the White House briefing room to deny that he was about to resign or be fired, describing the president as a “thoughtful” and “straightforward guy”.

In April this year he denied a report that he called Trump an “idiot”. In October he was said to have got into a shouting match with the national security adviser, John Bolton, over immigration.

Now CNN is not alone in its reporting that he has finally reached the end of the line.

The New York Times reported on Friday: “Mr Kelly and Mr Trump have grown weary of each other. But Mr Trump, according to several senior administration officials and people close to him, has so far been unable to bring himself to personally fire a retired four-star military general.”

And Maggie Haberman, the paper’s White House correspondent, tweeted: “Senior staff meeting canceled. Lights are off in Kelly’s office this morning, per a senior admin official. But as of an hour ago, he hadn’t been fired or resigned. There is a staff holiday dinner tonight that aides still expect him to attend.”