– President Donald Trump’s lead lawyer for the special counsel investigation, John Dowd, resigned Thursday as his strategy for cooperating with the inquiry grew increasingly at odds with Trump’s desire for a more aggressive posture.

Dowd, who took over the president’s legal team last summer and considered leaving several times, ultimately concluded that Trump was ignoring his advice, a person briefed on the matter said.

“I love the president,” Dowd said. “I wish him the best of luck. I think he has a really good case.”

His departure marked the most significant shake-up for Trump’s legal team in months and underscores the president’s growing frustration with the investigation by Special Counsel Robert Mueller into Russia’s election interference and possible ties to Trump associates as well as whether the president obstructed the inquiry.

The president has recently begun publicly assailing Mueller, a shift in tone that appears to be born of Trump’s concern that the investigation is bearing down on him more directly. Trump has also insisted that he should sit for an interview with the special counsel’s office, even though Dowd believed it was a bad idea.

“Yes, I would like to,” Trump said. “I would like to.”

Trump often keeps his own counsel, and whether he will agree to an interview is uncertain. But he is unmistakably veering toward the combative approach to the investigation that was supported by his longtime personal lawyer, Marc Kasowitz, who stepped back last summer but was still in contact with the president occasionally over the past several months. He could take on a larger role again, two people close to the president’s legal team said.

The president was said to be pleased with Dowd’s resignation, as he had grown frustrated with him, particularly over the weekend when Dowd called on the Justice Department to end the special counsel investigation. Dowd, who had forged relationships with the special counsel’s office, said at first that he was speaking for the president but later backtracked.

The president was angered with Dowd’s handling of the episode, telling people it was ham-handed and Dowd should not have backed off his initial statement.

Despite claiming otherwise on Twitter, the president has expressed displeasure with his legal team for weeks. He has met with veteran Washington lawyer Emmet Flood, who represented President Bill Clinton during impeachment, about coming inside the White House to serve as his top lawyer. Neither Dowd nor Jay Sekulow, the president’s other personal lawyer for the investigation, knew about the meeting at the time, and after the New York Times reported on it, they were said to be concerned that their standing had fallen. He tried to reassure them on Twitter.

“The Failing New York Times purposely wrote a false story stating that I am unhappy with my legal team on the Russia case and am going to add another lawyer to help out. Wrong. I am VERY happy with my lawyers, John Dowd, Ty Cobb and Jay Sekulow,” Trump wrote. “They are doing a great job.”

It is not clear who will take over the team.