Trump has for months obsessed publicly over the perceived disloyalty of his attorney general, tweeting again this week that he wished he’d picked someone else for the job. In private, Trump has leaned on Sessions to reverse his decision to recuse himself from Mueller’s sprawling probe — and his firing now over a refusal to do so, some say, would bolster Mueller’s case that Trump has tried to block that investigation from proceeding.

The president is aware that Sessions may have the upper hand, according to two senior administration officials, and his unrelenting campaign against his attorney general is in part fueled by that knowledge.

“He’s got a ton of leverage,” said Andrew McCarthy, a former federal prosecutor who has argued that Mueller’s appointment, without the identification of a specific underlying crime to be investigated, violated Justice Department regulations.

Everything Trump does in the way of personnel movements, if it even tangentially touches on this investigation, is a potential landmine for the president, McCarthy added.

Trump allies and legal experts agree that firing the attorney general is within the president’s rights as the head of the executive branch. But just as Richard Nixon’s 1973 decision to fire Watergate special prosecutor Archibald Cox triggered a wave of resignations and firings in the Justice Department — the Saturday Night Massacre — a decision by Trump to get rid of Sessions would unleash suspicions about Trump’s motivations.

“He attempted to persuade [Sessions] to un-recuse himself. Think how much worse it’d be if he fired him because he wouldn’t un-recuse himself,” said a Republican attorney close to the White House. “You’re going to be aggravating your problems if you do fire him.”

Others, however, argue that the damage is already done — because Trump’s request that Sessions retake control of the Russia investigation is as much about meddling in the Mueller probe as firing the attorney general over his refusal would be.

Regardless, obstruction of justice, including Trump’s efforts to persuade Sessions to reverse his decision to recuse himself from the investigation, is already a focus of Mueller’s investigation. According to The New York Times, the special counsel wants to ask the president questions including, “What did you think and do regarding the recusal of Mr. Sessions” and “What efforts did you make to try to get him to change his mind?”

Sessions recused himself from the Russia probe amid reports that he met twice in 2016 with Sergey Kislyak, then Russia’s ambassador to the U.S., despite having told senators during his confirmation hearings that he had no contacts with Russian officials during his time as an adviser to Trump’s presidential campaign. Sessions has denied any wrongdoing.

Trump returned to his grievance campaign against the attorney general on Wednesday, responding to South Carolina Republican Rep. Trey Gowdy’s suggestion that “he could have picked somebody else” to do the job: “I wish I did!”

Some administration officials have come to feel sympathy for Sessions, and describe the constant attacks on him from the president as personally painful for the AG. They view his commitment to stay in the post despite the president’s displeasure as honorable.

The White House declined to comment.

Republicans on Capitol Hill moved to protect Sessions months ago in the face of Trump’s parade of insults, with Senate Judiciary Committee Chairman Chuck Grassley saying in July that he will not hold hearings to confirm a successor if Sessions is dismissed.

“If Jeff Sessions is fired, there will be holy hell to pay,” Sen. Lindsey Graham (R-S.C.) told CNN the same month.

When asked why Trump doesn’t simply fire his attorney general if he is displeased with him, press secretary Sarah Sanders said on Wednesday: “The president has made his viewpoint very clearly known, and I don’t have any personnel announcements at this point.”

Sessions allies say he has vowed to stick it out. The immigration hard-liner has promised allies in the West Wing that he will never quit — he has told them that he understands the immigration agenda he is quietly implementing is worth the public humiliation of being publicly demeaned by the commander in chief.

But those close to Sessions concede that he is less effective in the job than he would be if he had a close working relationship with the president. A push for criminal justice reform, for example, led by Trump son-in-law and senior adviser Jared Kushner is proceeding apace inside the White House with the president’s approval — and over Sessions’ vehement objection.

“Sessions would be a really effective opponent if he had the president’s ear,” McCarthy said. “If he wants to be a very effective attorney general, he’s got to have a good relationship with the president.”