For years he was known as chief of staff to Vice President Dick Cheney and assistant to President Bush. On Wednesday, I. Lewis "Scooter" Libby became federal inmate No. 28301-016.

Libby, who was convicted in March of lying and obstructing an investigation into the leak of a CIA operative's identity, faces 2 1/2 years in prison.

The assignment of an inmate number by the U.S. Bureau of Prisons represents another step on the road to prison. Inmate numbers stay with prisoners even after their release.

Libby, however, is hoping that an appeals court will intervene and put the sentence on hold before he is ordered to surrender.

The U.S. Court of Appeals for the District of Columbia Circuit has not indicated how quickly it will rule. Lawyers in the case said Libby had not yet been assigned to a prison or given a date to surrender.

Special Prosecutor Patrick Fitzgerald opposes Libby's bid to delay his prison term. He says Libby does not have a good chance of having his conviction overturned and should begin serving prison time immediately.

Libby's friends have asked President Bush to step in and pardon him, a request that Bush has sidestepped while the legal case drags on.

Libby, 56, is the only person charged in the leak scandal, which erupted after CIA operative Valerie Plame's identity was revealed in a 2003 syndicated newspaper column. Libby was not the source for that leak and neither of the two Bush administration officials who provided the information were ever charged.

When confronted by prosecutors and FBI agents, however, Libby lied about how he learned about Plame and whom he told, a jury found. He is the highest-ranking White House official sentenced to prison since the Iran-Contra scandal in the 1980s.

The Bureau of Prisons does not say where its inmates will serve until they begin their sentence. Normally, prisoners are assigned to facilities within 200 miles of home. As a nonviolent, first-time offender, Libby likely will be placed in a minimum security prison camp.