High-level sniping over the commutation President Bush gave to a former White House aide, I. Lewis Libby Jr., broke out in earnest yesterday, as the judge who sentenced Libby openly disputed Mr. Bush’s stated rationale and the president publicly suggested that a former State Department official could have headed off the whole investigation by going public about his role in the leak of a CIA operative’s identity.

In 10-page order, Judge Reggie Walton upheld the part of Mr. Bush’s commutation that left in place a two-year period of supervised release for Libby, a former chief of staff to Vice President Cheney. However, in a lengthy footnote, the judge forcefully took issue with the president’s statement describing the 2 1/2-year sentence for Libby as overly severe.

“It is fair to say that the Court is somewhat perplexed as to how its sentence could be accurately characterized as ‘excessive,'” Judge Walton wrote. “Although it is certainly the president’s prerogative to justify the exercise of his constitutional commutation power in whatever manner he chooses (or even to decline to provide a reason for his actions altogether), the Court notes that the term of incarceration imposed in this case was determined after a careful consideration of each of the requisite statutory factors … and was consistent with the bottom end of the applicable sentencing range as properly calculated under the United States Sentencing Guidelines.”

In March, a jury convicted Libby of obstruction of justice, lying to the FBI, and perjury before a grand jury investigating the leak about the CIA officer, Valerie Plame. Neither Libby nor anyone else was charged with leaking Ms. Plame’s CIA tie.

At a press conference yesterday, Mr. Bush seemed to indicate that a former deputy secretary of state, Richard Armitage, should have spoken out sooner about being a source of the leak that led to Ms. Plame being identified in a newspaper column. Mr. Armitage, who did not return a call seeking comment yesterday, disclosed his role to investigators early on, but said nothing to the public about it for more than three years.

“I’ve often thought about what would have happened had that person come forth and said, ‘I did it.’ Would we have had this, you know, endless hours of investigation and a lot of money being spent on this matter?” Mr. Bush said.

The president did not mention Mr. Armitage by name, but Libby’s allies have expressed ire at him in particular. In 2003, he disclosed the CIA link to the columnist who first published Ms. Plame’s name, Robert Novak. Libby, a White House political adviser, Karl Rove, and a former White House press secretary, Lawrence Ari Fleischer, have acknowledged discussing Ms. Plame’s CIA connection with one or more journalists.

Mr. Bush did not note that while the matter was under investigation, prosecutors, the FBI, and the White House instructed all government officials to refrain from public comment in order to allow the probe to proceed.

The president did not respond directly to a question yesterday about whether he was disappointed in those who orchestrated the leak. “It has been a tough issue for a lot of people in the White House, and it’s run its course, and now we’re going to move on,” Mr. Bush said.

Judge Walton said he left the two-year probation for Libby in place “with great reservation” because the statute governing supervised release appears to require that a defendant serve some jail time first. “The President has effectively rewritten the statutory scheme on an ad hoc basis to make the punishment created by Congress applicable to a situation Congress clearly did not intend,” the judge wrote.

The judge also implied that Mr. Bush’s contention that the sentence was too long flew in the face of the position his administration took in a similar case just decided by the Supreme Court and Attorney General Gonzales’s support for making sentencing guidelines mandatory.

The White House did not reply to a request for comment on Judge Walton’s ruling.