Mr. Trump has shown no particular interest in Mr. Libby’s case before. In 2015, during his campaign for the White House, Mr. Trump was asked if he would pardon Mr. Libby and declined to say, calling it an irrelevant issue. It was unclear when Mr. Trump would issue the pardon, which was first reported by ABC News.
Mr. Libby was not charged with the leak itself and has long argued that his conviction rested on an innocent difference in memories between him and several witnesses, not an intent to deceive investigators. Although Mr. Bush’s clemency order kept him from going to prison, Mr. Libby’s conviction nonetheless remained intact and he was disbarred as a lawyer as a result. He was not reinstated to the bar until 2016.
Among the allies from the Bush administration who have argued that he was treated unfairly is John R. Bolton, an ally of Mr. Cheney’s who served as Mr. Bush’s ambassador to the United Nations and started this week as Mr. Trump’s national security adviser. Other allies of Mr. Libby’s include Joseph diGenova and Victoria Toensing, a husband-and-wife team of lawyers who recently talked about going to work for Mr. Trump before deciding against it because of a client conflict.
A pardon by Mr. Trump would amount to official forgiveness, not exoneration. A pardon does not signify innocence but does eliminate many consequences of a conviction, such as any effect on the right to vote, hold elective office or sit on a jury. As a practical matter, those seeking pardons hope it will erase or ease the stigma of a criminal conviction.
Mr. Libby’s prosecution became a symbol of the polarizing politics of the Iraq war during the Bush administration. Ms. Wilson’s husband, Joseph C. Wilson IV, was a former diplomat who wrote an op-ed article in The New York Times in 2003 implying that Mr. Cheney ignored evidence that argued against the conclusion that Iraq was actively seeking to build nuclear weapons.
To undercut Mr. Wilson’s criticism, administration officials told reporters that he had been sent on a fact-finding mission to Niger because his wife worked for the C.I.A., not at the behest of Mr. Cheney. But federal law bars the disclosure of the identities of C.I.A. officials in certain circumstances and the leak prompted a special prosecutor investigation.
Charged with lying to investigators about his interactions with journalists, Mr. Libby insisted he simply remembered events differently. But his version of events clashed with the testimony of eight other people, including fellow administration officials, and a jury convicted him. Mr. Bush decided that the prison sentence was “excessive,” but he said he would not substitute his judgment for that of the jury when it came to the question of Mr. Libby’s guilt.
Mr. Libby’s advocates argued that Patrick J. Fitzgerald, the special prosecutor, went too far because he had already discovered that the first administration official to disclose Ms. Wilson’s identity to a journalist was Richard Armitage, the deputy secretary of state in Mr. Bush’s first term, who was not charged. They also argued that Ms. Wilson was not undercover at the time and her employment was well known. Ms. Wilson has denied that she recommended her husband for the mission to Niger and said her career as a C.I.A. official was “over in an instant” once her identity was leaked.
The case tested the limits of journalistic independence. Judith Miller, then a reporter for The Times, went to prison for 85 days rather than disclose that Mr. Libby had discussed Ms. Wilson with her. She was freed after Mr. Libby released her from any promise of confidentiality.
The issue became a major point of contention between Mr. Bush and Mr. Cheney in the last days of the administration in late 2008 and early 2009. Mr. Cheney repeatedly pressed Mr. Bush to go beyond his commutation and issue a full pardon, bringing it up so often that the president grew irritated by the matter.
Mr. Bush assigned White House lawyers to examine the case, but they advised him the jury had ample reason to convict Mr. Libby and the president rebuffed Mr. Cheney’s request. Mr. Bush told aides that he suspected that Mr. Libby had thought he was protecting Mr. Cheney, the real target of the investigation.
Mr. Cheney snapped at Mr. Bush. “You are leaving a good man wounded on the field of battle,” he told him when informed of the decision.
Mr. Bush was taken aback. It was probably the harshest thing Mr. Cheney ever said to him during their eight years in office together and was meant to attack Mr. Bush’s sense of loyalty to his own troops in a time of war.
“The comment stung,” Mr. Bush wrote in his memoir. “In eight years, I had never seen Dick like this, or even close to it. I worried that the friendship we had built was about to be severely strained, at best.”
The case has its connections to Mr. Trump because Mr. Fitzgerald was friends with James B. Comey, who was then the deputy attorney general who assigned him the investigation after the attorney general recused himself. Mr. Cheney long suspected that Mr. Comey was taking revenge for a dispute between them over the legality of a surveillance program.
Mr. Comey would go on to become the director of the F.B.I. who was fired by Mr. Trump last year in the midst of the Russia investigation. His dismissal led the deputy attorney general, Rod J. Rosenstein, who was in charge after the recusal of Attorney General Jeff Sessions, to appoint Robert S. Mueller III as special counsel to take over the inquiry.
Mr. Trump has been notably conservative about using his clemency power. He has issued only two pardons and commuted only one sentence in nearly 15 months in office, according to the Justice Department. Most notably he pardoned Joe Arpaio, the former Arizona sheriff whose crackdown on illegal immigrants earned him a criminal contempt conviction.