Alan Dershowitz, the lawyer and professor emeritus at Harvard Law School, assumed his standard role Thursday in the feedback loop connecting conservative cable news and President Trump’s Twitter pronouncements.

Dershowitz joined Fox News host Tucker Carlson to denounce purported discussions within the Justice Department about using the 25th Amendment to remove the president. The talks were confirmed by Andrew McCabe, the former acting FBI director, in an interview with “60 Minutes” set to air in full this weekend, CBS journalist Scott Pelley said Thursday, when a clip from the interview was released. The amendment, which creates a process for the vice president and Cabinet to declare a president unfit, was apparently explored by top Justice Department officials in May 2017 as they became alarmed by the president’s decision to fire James B. Comey, the former FBI director.

The advance clip does not include talk of the 25th Amendment but rather focuses on McCabe’s decision to authorize a probe into Trump’s possible ties to Russia out of fear that he would soon follow Comey in being dismissed.

Trump earlier on Thursday had launched a general attack on McCabe, impugning his personal character.

After watching Carlson’s show on Fox, his criticism became more specific. He quoted Dershowitz’s denunciation of the alleged consideration of the 25th Amendment as a means of removing the 45th president.

The amendment, which grew out of the assassination of President John F. Kennedy in 1963, was proposed in 1965 and ratified two years later. It spells out the line of succession to the presidency and created a mechanism for an acting president to be ousted if the vice president and a majority of the Cabinet deem the head of the executive branch “unable to discharge the powers and duties of his office.” On numerous occasions before its introduction, Congress had found itself without clear guidelines for replacing a president unable to fulfill his duties, stretching back to the 1841 death of President William Henry Harrison a month into his term.

Recently, it has gained currency as a possible arrow in the quiver of those bent on ousting Trump, circumventing impeachment procedures that would require the Republican-controlled Senate to convict one of its own.

Reporting by The Washington Post and other outlets has indicated that the conversations, in McCabe’s telling, also involved Deputy Attorney General Rod J. Rosenstein. They became so serious, according to the former FBI deputy, that the No. 2 at the Justice Department suggested wearing a wire to record the president. Rosenstein has obliquely denied the other man’s account.

“Now the suspicions of many are confirmed by one of the players in it,” Carlson declared Thursday. “The Department of Justice discussed trying to remove the president using the 25th Amendment.”

Dershowitz, who is an informal adviser to the president, was unambiguous.

“If that’s true, it is clearly an attempted coup d’etat,” he said.

The lawyer, who has defended the likes of O.J. Simpson, has made headlines for his vehement objection to the Russia investigation. He complained last summer that his defense of the president had made him persona non grata on Martha’s Vineyard, the elite enclave off the coast of Cape Cod.

“Let’s take the worst case scenario,” Dershowitz said. “Let’s assume the president of the United States was in bed with the Russians, committed treason, committed obstruction of justice. The 25th Amendment is simply irrelevant to that. That’s why you have an impeachment provision.”

The amendment, he argued, spoke to a condition of “medical or psychological incapacity.” It could not be a recourse even in the event of “the most extreme crimes, which there’s no evidence were committed,” he said. He labeled the discussions “a despicable act of unconstitutional power grabbing” and said he agreed with Carlson’s assessment that they recall “what happens in third-world countries.”

Dershowitz, in a final flourish, issued a challenge to “any left-wing person” or “any of my colleagues who are in the get-Trump-at-any-cost camp to come on television and justify the use of the 25th Amendment other than for physical or psychiatric incapacity.”

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