Opening his defence at his perjury trial, lawyers for Lewis “Scooter” Libby produced a memo written by Mr Cheney, the Vice-President, showing his chief of staff’s concerns that he was being sacrificed to save Mr Rove from criminal indictment.

Mr Libby is accused of lying to FBI agents about conversations he had with journalists about Valerie Plame, a CIA agent. She is the wife of Joseph Wilson, a prominent critic of the Iraq war. When her name appeared in the press in 2003, her husband claimed that she was an undercover agent and had been deliberately “outed” by the White House as retribution for his claims that the Bush Administration twisted prewar intelligence. A leak investigation followed.

Mr Libby’s lawyers claimed yesterday that White House officials rallied around Mr Rove but stopped short of protecting Mr Libby. Having been asked by Mr Cheney to rebut Mr Wilson’s criticisms, Mr Libby felt betrayed and sought out his boss.

“They’re trying to set me up. They want me to be the sacrificial lamb,” the attorney Theodore Wells said, recalling Mr Libby’s end of the conversation. “I will not be sacrificed so Karl Rove can be protected.” Mr Rove was one of two sources for the offending “leak” article by the conservative columnist Robert Novak.

Mr Cheney’s notes from that meeting underscored Mr Libby’s concern, Mr Wells said.

“Not going to protect one staffer and sacrifice the guy that was asked to stick his neck in the meat grinder,” the note said.

By pointing the finger at Mr Rove, whom he referred to as “the lifeblood of the Republican Party,” Mr Wells sought to cast Mr Libby as a scapegoat.

Nobody, including Mr Libby, has been charged with illegally leaking Ms Plame’s name. Mr Libby denies lying to investigators over what he told journalists about Ms Plame.

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