Prosecutors urged Buckwalter "not to repeat" his earlier decision.
"Defendant Fumo does not deserve - and justice does not permit - a discounted sentence for a successful track record of legitimate service," Assistant U.S. Attorneys Bob Zauzmer and John Pease wrote in their 84-page sentencing memo.
They said that if Buckwalter decides that the recommended advisory guideline sentence is too long, then Fumo should get a minimum 15-year sentence.
The feds' sentencing memo doesn't plow much new ground.
Fumo, 68, was convicted in March 2009 of 137 corruption counts after a lengthy trial. A jury found that he had used Senate staff as personal and political minions, bilked two charities and destroyed emails to cover his tracks.
"No variance is warranted in this case," prosecutors wrote. "There should not be a downward variance based on Fumo's public service. The fact that he was a state Senator is an aggravating factor in this case, not a mitigating factor."
Defense attorney Dennis Cogan said last month that there was "no reason" why Fumo should get more prison time.
Cogan described Fumo as someone who is depressed, has gained weight and has grown a beard during his imprisonment. He is slated to be released in August 2013.
The defense will file its sentencing recommendation by Oct. 28.