WASHINGTON — In the latest sign of disarray in President Trump’s legal team, a lawyer who he said last week would come on board to help handle his response to Special Counsel Robert Mueller’s Russia investigation will no longer be part of the effort.

The development came three days after John Dowd, who had been Trump’s top attorney handling the Russia inquiry, resigned amid strategy disputes with the president.

Trump is now left, at least temporarily, without a traditional criminal defence attorney as Mueller’s team appears to be entering a critical phase in its investigation into Moscow’s interference in the 2016 election and whether the president’s campaign cooperated with Russia in this effort.

Joseph diGenova, the lawyer Trump wanted to replace Dowd, has often stridently defended the president on Fox News Channel and cast the Mueller probe as a conspiracy against him. Trump enjoyed the TV appearances and wanted diGenova on his team even though he did not know him, officials say.

But in a statement on Sunday, a spokesman for Trump’s legal team said both diGenova and his wife, Victoria Toensing, who is also a lawyer, would not be working on the Russia probe because clients they were already representing in connection with the investigation posed conflicts of interest.

“The President is disappointed that conflicts prevent Joe diGenova and Victoria Toensing from joining his Special Counsel legal team,” said Jay Sekulow, counsel to Trump. “However, those conflicts do not prevent them from assisting the President in other legal matters. The President looks forward to working with them.”

The unravelling of the president’s legal team has left his advisers concerned. People familiar with the situation said the president has been counselled by friends that he needs to find a new lawyer to quarterback his team and efforts are underway by people close to Trump to try to hire a new lawyer.

Before his resignation Thursday, Dowd had been Trump’s main point of contact with Mueller’s office and had been helping to negotiate the terms for an interview between the president and the special counsel’s team as it examines whether Trump obstructed justice by seeking to shut down the investigation, which was being conducted by the FBI until Trump fired FBI Director James Comey in May of last year. Mueller was then appointed special counsel by Deputy Attorney General Rod Rosenstein.

Trump’s legal effort is now led by Sekulow, a conservative attorney and radio host who has concentrated on constitutional issues, and assisted by Ty Cobb, a White House lawyer paid by taxpayers to represent the institution of the presidency rather than Trump personally. Cobb too has occasionally drawn the president’s ire, people familiar with the team have said.

A number of white-collar attorneys in Washington said the president has been unable to attract top-flight talent as he looks to overhaul his legal team, with major firms fearful that an affiliation with Trump and the Russia case could impact their ability to attract other clients and hire new lawyers.

Trump has recently been relying on Marc Kasowitz, who led his legal team until this summer and has represented Trump in several cases over the years. Kasowitz and Trump clashed over a number of issues, including Kasowitz’s belief that Jared Kushner, the president’s son-in-law and a top White House aide, needed to leave the administration because of the potential legal problems he faced due to the probe and the potential problems they could cause Trump. After Dowd’s hiring, Kasowitz took a diminished role in handling the case.

Ultimately, said one person close to Trump’s legal team, “He’s his own lawyer. Always has been and always will be.”

They added: “You know what they say about a ‘lawyer’ who has himself as a client.”

Trump’s issues with diGenova and Toensing went beyond their conflicts, said a person who spoke to the president recently. After meeting with the husband-and-wife team on Thursday — when diGenova’s hiring had already been announced — the person said Trump found himself less impressed with diGenova than he had been while watching the former US attorney on television.

Three days later, diGenova’s was no longer joining the legal team.

Trump did not closely research diGenova or even consult with top aides, including Chief of Staff John Kelly and White House counsel Donald McGahn, before hiring him.

Trump had hoped diGenova could serve as a surrogate in television interviews and play the role of attack dog in criticising the Mueller probe.

Sekulow approached diGenova two weeks ago about joining the team, but it turned out that he and his wife run a law firm that represents clients with interests that would conflict with those of the president.

One is Mark Corallo, a former spokesman for Trump’s legal team and a witness in the Mueller investigation. He resigned in the wake of a dispute over the president’s role in a misleading statement about his son, Donald Trump Jr., and campaign aides’ meeting with a Russian lawyer offering “dirt” on 2016 opponent Hillary Clinton.

In a burst of tweets early Sunday morning, Trump insisted that he is “very happy” with his existing legal team.

Trump said that many “lawyers and top law firms want to represent me in the Russia case” and that people should not “believe the Fake News narrative that it is hard to find a lawyer who wants to take this on.”

“Fame & fortune will NEVER be turned down by a lawyer, though some are conflicted,” the president said, adding that “there was NO COLLUSION with Russia.”

Earlier this month, Trump denied there were any problems regarding his legal team and eight days later Dowd was out.

Trump’s struggles are reminiscent of his difficulties in the spring of 2017 when he was first seeking new lawyers to represent him in the Russia probe. He interviewed a half-dozen high-profile legal stars in the white-collar defence bar, including Emmet Flood, Brendan Sullivan and A.B. Culvahouse; all of them declined.