The Republican chairman of the Senate Judiciary Committee asked the attorney general in a Friday letter to hand over a complete record of documents, conversations and other communications pertaining to discussions about removing President Trump from office, promising to investigate “what amounts to a coup” against him, Graham wrote.

The letter from Sen. Lindsey O. Graham (R-S.C.) to Attorney General William P. Barr makes good on a promise Graham made last month to investigate whether top law enforcement officials discussed invoking the 25th Amendment to strip Trump of the presidency. In an interview on “60 Minutes” last month, former FBI deputy director Andrew McCabe said that Deputy Attorney General Rod J. Rosenstein raised the idea — and even offered to wear a wire to record his conversations with Trump — to build a case for his removal and persuade Cabinet members to join the effort.

The conversations McCabe cited took place in the wake of Trump’s move to fire FBI Director James B. Comey, a decision that continues to be a central focus of lawmakers investigating whether the president has obstructed the federal investigation of his campaign. The New York Times first reported last year that McCabe had made note of Rosenstein’s alleged proposal in a memo; Rosenstein denied that he had. Graham promised last month that his committee would also subpoena Rosenstein and McCabe if necessary.

The letter is Graham’s latest effort to pick up where House Republicans left off last year in their probe of top law enforcement officials and how they handled federal investigations into Trump’s alleged Russia ties and Hillary Clinton’s use of a private email server.

On the Senate floor Thursday, Graham also repeated his call for the Justice Department to appoint a second special counsel to look into FBI and Justice Department officials’ conduct and whether political bias affected decisions that were made in the course of those investigations.