Former State Sen. Vincent J. Fumo faces a possible prison term of 21 to 27 years under federal sentencing guidelines for his corruption conviction, prosecutors disclosed yesterday.

The much-anticipated calculation, made by a senior probation official, was made known in a prosecution court filing as Fumo's defense lawyers sought to delay sentencing, now set for July 14.

The lawyers said they asked for a postponement until at least late September so they can better prepare for what is bound to be a protracted and hard-fought proceeding on the appropriate punishment for the once-powerful politician.

Dennis J. Cogan, Fumo's lead counsel, told U.S. District Judge Ronald L. Buckwalter that he would argue for a more lenient sentence than the guideline range.

Cogan said that the calculation was preliminary, that it was based only on the prosecution's view of the case, and that the defense would soon weigh in with objections.

Assistant U.S. Attorneys John J. Pease and Robert A. Zauzmer objected to a delay.

"Every day that Fumo remains free is another day that justice is denied," they stated in a court filing that also disclosed the 21-to-27-year guideline.

Fumo, 66, a Democrat who enjoyed extensive clout in Philadelphia and Harrisburg for decades, was convicted in March of all 137 counts against him in a wide-ranging corruption indictment.

He was found guilty of defrauding the state Senate by getting his staff to perform political-campaign and personal errands for him on state time, and defrauding the nonprofit Citizens' Alliance for Better Neighborhoods by getting it to pay for thousands of purchases for him.

Fumo also was found guilty of defrauding the Independence Seaport Museum by getting free trips on yachts provided by the museum, and of obstructing the FBI investigation and tax violations.

The guidelines' range of 262 to 327 months, calculated by a senior probation official, is outlined in a draft presentence report, and the prosecution and the defense are expected to battle over the final calculation.

The guidelines calculation, while advisory, is expected to be carefully considered by Buckwalter, who presided over the five-month trial.

Cogan said Washington lawyer Samuel Buffone of the law firm Ropes & Gray was recently retained to help with the sentencing and the appeal - and also needs time to familiarize himself with the case.

"The trial of this case has already consumed a significant amount of time, and the additional time necessary to permit Mr. Fumo to adequately prepare for sentencing will not unnecessarily prolong its conclusion," wrote Cogan, who filed the postponement request with Buffone and defense lawyer Peter Goldberger.

Pease and Zauzmer said in their court filing that Fumo, while free on bail pending sentencing, "continues to enjoy the considerable benefits of his personal fortune without attempting to repay any of the funds he stole from his victims."

They said Fumo "shamelessly perjured himself dozens of times" during the trial and has "repeatedly thumbed his nose" at law-enforcement officials.

Now, they wrote to the judge, Fumo is trying to postpone punishment, and that should not be tolerated.