Walker hopes this new offer holds the key to his cell door.
His lawyers are optimistic, too, noting in a July letter to the Justice Department that he meets all the criteria for possible release, including serving a sentence that would have been substantially lower if imposed today.
Add to that support from an unlikely corner: Walker's trial judge, who's on record urging the president to reduce the sentence to 20 years. He calls a life term "excessive and disproportionate" and says Walker's time in prison has been "a handbook on self-improvement."
Scott Walker's story reflects a debate now intensifying in political and legal circles over decades of get-tough laws that have jammed America's prisons with drug offenders, produced a growing outcry for sentencing reform and posed perhaps the trickiest question of all: How do you make sure the punishment fits the crime?
Walker says he knows he did wrong and should have paid a price. But surely not for the rest of his life.
"From the time you're a kid ... you hear America is the land of redemption, the land of liberty and the land of justice," he says, sitting in a conference room at the Federal Correctional Institution here in southern Illinois. "Where's the land of mercy? Is there mercy for people who have made mistakes?"
Walker pauses, then adds:
"I believe everyone deserves a second chance in life."
Looking back, Walker says he's ashamed of what he did in his teens and 20s.
"I find it very hard to relate to the person that I once was, which makes it all the more difficult for me to live with my past mistakes," he wrote in a 2009 letter to one of his lawyers. "Age and experience have given me new values, hopes, dreams and goals. ... This is something we don't comprehend when we are young."
Walker now blames his past behavior on immaturity. "You feel like you're invincible, that you're never going to grow old," he says.
With straight brown hair parted down the middle framing his unlined face, Walker looks a decade younger than 42. Speaking with a slight twang, he remembers being so naive he thought he could be arrested for drug dealing only if caught in the act.
Growing up in southern Illinois, Walker started using marijuana around age 14, then graduated to meth, becoming a hard-core addict. He played guitar in a band, and drugs, he says, were an accessory to his rock-'n'-roll lifestyle.
"Scott was a very strong-willed young man," says Keith Shelton, his stepfather. "He did not listen. He didn't want to listen. He felt like most kids do. ... You're made out of steel. You're never going to get caught. Things are always going to be the way you want them to turn out."