The life-size portrait, "Benefits Supervisor Sleeping," shows Sue Tilley, an employee at a British job center who posed for Freud on her days off for four years in the 1990s. She told The Independent she would like to buy the picture herself -- if she had the money.
The painting, which was sold privately in 1995, could fetch as much as $36 million at Christie's, the British newspaper said. That would be far more than the $23 million paid last year for Jeff Koons' "Hanging Heart."
Tilley, known as "Big Sue," was introduced to Freud by an artist friend who also served as a model.
"I think he probably picked me because he got value for money," Tilley said. "He got a lot of flesh."
Freud, now 85, was born in Berlin and moved to London with his parents at the age of 11. He is a grandson of the noted psychologist Sigmund Freud.