A federal judge said Thursday he will not delay a 2 1/2-year prison sentence for I. Lewis "Scooter" Libby in the CIA leak case, a ruling that could send the former White House aide to prison within weeks.

U.S. District Judge Reggie B. Walton's decision will send Libby's attorneys rushing to an appeals court to block the sentence and could force President Bush to consider calls from Libby's supporters to pardon the former aide.

No date was set for Libby to report to prison but it's expected to be within six to eight weeks. That will be left up to the U.S. Bureau of Prisons, which will also select a facility.

"Unless the Court of Appeals overturns my ruling, he will have to report," Walton said.

Libby's wife, Harriet Grant, wiped tears away from her eyes but Libby was stoic as Walton ruled.

Libby, the former chief of staff to Vice President Dick Cheney, was convicted in March of lying to investigators and obstructing Special Prosecutor Patrick Fitzgerald's inquiry into the 2003 leak of a CIA operative's identity.

Libby's supporters have called for President Bush to wipe away Libby's convictions. Bush publicly has sidestepped pardon questions, saying he wants to let the legal case play out. A delay would give Bush more time to consider the requests.

"Scooter Libby still has the right to appeal, and therefore the president will continue not to intervene in the judicial process," White House spokeswoman Dana Perino said. "The president feels terribly for Scooter, his wife and their young children, and all that they're going through."

Libby thanked federal marshals but did not take questions from reporters as he left the courthouse with his wife and lawyers. Fitzgerald also left without commenting.

Walton never appeared to waver from his opinion that a delay was unwarranted. After 12 prominent law professors filed documents supporting Libby's request, the judge waved it off as "not something I would expect from a first-year in law school."

He also said he received several "angry, harassing, mean-spirited" letters and phone calls following his sentencing but said they wouldn't factor into his decision.

Libby is the highest ranking government official ordered to prison since the Iran Contra affair. His monthlong trial offered a rare glimpse into the White House in the early days of the Iraq war.

Trial testimony showed that Cheney was eager to beat back criticism of prewar intelligence. One of the administration's most outspoken critics in mid-2003 was former Ambassador Joseph Wilson.

Amid a flury of news coverage of that criticism, Bush administration officials leaked to reporters that fact that Wilson's wife, Valerie Plame, worked as an undercover analyst for CIA. That disclosure in a syndicated newspaper column touched off a leak investigation that brought senior White House officials, including Bush and Cheney, in for questioning.

Libby argued he had a good chance of persuading an appeals court that, when Attorney General John Ashcroft and other senior Justice Department officials recused themselves from the leak investigation, they gave Fitzgerald unconstitutional and unchecked authority.

Walton was skeptical, saying the alternative was to put someone with White House ties in charge of an investigation into the highest levels of the Bush administration.

"If that's going to be how we have to operate, our system is going to be in serious trouble with the average Joe on the street who thinks the system is unfair already," Walton said.

Libby's newly formed appellate team — Lawrence S. Robbins and Mark Stancil — will seek an emergency order delaying the sentence. The U.S. Court of Appeals for the District of Columbia Circuit is not sitting right now, however, and attorneys worried about how fast the request would be heard.

The appeals court has several conservative jurists, but that doesn't necessarily mean Libby will get a pass. Walton is a Republican judge whom Bush put on the bench in his first term.