WASHINGTON — The lobbyist known for lavishing politicians with football tickets or whisking them away on exotic golf junkets, Jack Abramoff, will start life today with a new identity: federal inmate no. 27593–112.

Abramoff is to report to federal prison to begin serving a nearly six-year prison sentence for a fraudulent deal to buy a fleet of casino ships in Florida. He also is awaiting sentencing for corrupting government officials and their staff members.

If it were up to the Justice Department, Abramoff wouldn’t be heading to prison — at least not yet. He could hold the key to a sweeping corruption case involving Congress, members of the Bush administration and their aides, and prosecutors said putting their star witness behind bars would impede the investigation.

But a Miami federal judge refused to delay the sentence, meaning Abramoff’s cooperation will have to continue from prison. Abramoff’s lawyers had no comment.

Abramoff was originally assigned to a federal prison in Pennsylvania about four hours away from Washington. Prosecutors wanted him assigned to a prison in Cumberland, Md., about two hours away.

The Justice Department said the issue has been resolved and, though the Bureau of Prisons will not comment on where Abramoff will report, prison officials began making preparation for a crush of reporters outside the Cumberland prison.

Abramoff enjoyed access and influence across Capitol Hill, from his close ties to members of congress to his hundreds of contacts with White House officials. He kept his powerful friends flush with campaign cash, gifts, and trips such as a $92,000 chartered jet to Scotland for a golf outing with Rep. Bob Ney, Bush administration official David Safavian, and congressional aides.

Ney, an Ohio Republican who recently resigned, became the first congressman convicted in the case when he confessed last month that he accepted took official actions on behalf of Abramoff’s clients in exchange for his gifts and campaign donations.

The investigation had already ensnared Ney’s former chief of staff and two aides to a former House majority leader, Tom DeLay. The investigation cost Mr. DeLay his leadership seat before he ultimately resigned, and it contributed to the Election Day defeat of Senator Burns, a Republican of Montana.

Safavian was sentenced in October to 18 months in prison for lying to investigators about his ties to Abramoff. He is asking a federal judge to postpone his sentence until he can appeal his conviction.

Mr. Burns, who received about $150,000 in Abramoff-related donations and whose aides traveled on the lobbyist’s jet to the 2001 Super Bowl, has denied any wrongdoing. Though two of Mr. Delay’s aides have pleaded guilty, the former majority leader maintains his innocence and has not been charged.