Prosecutors and defense lawyers for a former White House aide, I. Lewis Libby Jr., face a deadline Friday to give their final recommendations on the sentence he should receive for his conviction on charges of perjury, obstruction of justice, and lying to the FBI.

However, the real cliffhanger at the sentencing hearing, set for June 5, is not what punishment Judge Reggie Walton imposes, but whether he allows Libby to remain free while pursuing his appeal.

“That’s the big question everyone is watching,” a law professor specializing in sentencing issues, Douglas Berman of Ohio State University, said.

Bail for Libby would amount to a reprieve for President Bush, who would then have until next year to make the politically sensitive decision about a pardon for the former chief of staff to Vice President Cheney. However, if the judge orders Libby jailed forthwith, Mr. Bush will face intense and immediate pressure from many of his supporters to commute the sentence or grant a pardon.

A former U.S. attorney for the capital, Roscoe Howard Jr., said he doubts Judge Walton will allow Libby to delay serving his sentence until his appeals are resolved. “I don’t see that here,” the ex-prosecutor said.

Federal law dictates that bail pending appeal be denied unless the appeal raises “a substantial question of law or fact” that could reverse the conviction or have a significant affect on Libby’s sentence.

“Most people I talked to who followed the trial thought that the government’s evidence, regardless of whether you though the prosecution was proper, was pretty strong,” Mr. Howard said.

During the trial, Judge Walton expressed little concern that the appeals court would disagree with his rulings. “If I get reversed on that one, maybe I need to hang up my spurs,” he said after deciding a dispute stemming from Libby’s decision not to testify in his own defense.

Libby was convicted in March on four felony charges: one count of obstruction of justice, one count of lying to the FBI, and two counts of perjury. The charges were brought by a special prosecutor, Patrick Fitzgerald, in connection with an investigation into the disclosure of the identity of a CIA operative, Valerie Plame. No one was ever charged for leaking, but Libby was accused of lying when he told investigators and a grand jury that he thought for a time that journalists were the first to inform him of Ms. Plame’s CIA connection.

Libby faces a maximum possible sentence of 25 years in prison. However, lawyers not involved in the case said federal sentencing guidelines seem to call for 15 to 21 months of incarceration. Mr. Berman said there could be “a lot of flex” in the calculations, but not enough to allow the judge to impose probation instead of jail. “I would be shocked if the guidelines add up to allow for a non-prison sentence,” the professor said.

Under a 2005 Supreme Court decision, Judge Walton has to consider the guidelines, but is not obligated to follow them. “He’d have to say, ‘I don’t think the guidelines are appropriate under the circumstances,’ and he’d have to explain,” Mr. Berman said. Prosecutors would be free to appeal a sentence below the range and the defense could appeal one above it.

The defense is expected to give Judge Walton letters written on Libby’s behalf by his friends and supporters. “I just basically outlined all Scooter Libby’s virtues and strong points and talked about his integrity,” a former ambassador who has raised money for Libby’s defense, Richard Carlson, said. “Libby’s been a great public servant and I hope the judge takes that into consideration, particularly when deciding whether he can stay home with his family and continue working on all of the appeals.”

The prosecution and defense declined to preview their presentations yesterday. However, in a recent memo to Libby’s supporters, a defense lawyer urged those writing to Judge Walton not to paint the case as a political vendetta. “It is not acceptable … to criticize the jury, the prosecutors, or the court, or to denigrate any person involved in the process, including the witnesses,” the attorney, William Jeffress Jr., wrote, according to the Washington Post.

Mr. Howard noted that the emphasis on Libby’s history of public service, which dates back to a State Department stint in the 1980s, could hurt the former official by underscoring that he abused a position of trust. “They don’t reward you for that. They punish you for it,” the former prosecutor said.

Libby’s claim of innocence also makes it difficult for him to express the contrition that can bring a lenient sentence. “It’s tough to sit up there and say … ‘None of this happened,’ but he needs to address the court somehow. He’s got to,” Mr. Howard said.

A White House spokeswoman, Lea Anne McBride, declined to comment on whether Mr. Cheney wrote a testimonial for his former aide. In other cases, government officials who wrote judges on behalf of a criminal defendant have faced discipline for muddling the Justice Department’s message to the court. Ms. McBride said she could not address whether White House lawyers had given advice on that point.

Mr. Carlson said he wants Mr. Bush to offer a pardon, even if there is some political fallout. “People I know and admire are hoping the president will step up and do the right thing,” Mr. Carlson said.