If federal prosecutors get their way, convicted former Illinois Governor Rod Blagojevich’s famous jet black hair will turn gray behind prison walls.

In court filings, they asked a federal judge to hand down a sentence of 15-20 years because of “Blagojevich’s extensive corruption of high office, the damage he caused to the integrity of Illinois government, and the need to deter others from similar acts.”

In June, after a second trial, the 54-year-old Blagojevich was found guilty of trying to sell Barack Obama’s vacated Senate seat and shaking down constituents for campaign contributions. Prosecutors argued that the former governor’s actions were not isolated, but “part and parcel of an approach to public office that defendant adopted from the moment he became governor in 2002.”

Last week, a former Blagojevich fundraiser and political fixer, Tony Rezko, who also raised money for Barack Obama’s Senate campaigns, was sentenced to 10 years in prison. Prosecutors say Blagojevich deserves an even stiffer sentence because, unlike Rezko, he held public office. Defense attorneys are expected to ask for a far lighter sentence or even probation.

U.S. District Judge James Zagel, who presided over the trial, is scheduled to sentence Blagojevich next week.