PHILADELPHIA — Two of three U.S. judges hearing an appeal of former Pennsylvania Sen. Vince Fumo’s corruption sentence suggested Wednesday that the 55-month sentence is flawed.

Fumo, 68, was perhaps the most powerful Pennsylvania lawmaker in a generation, controlling scores of jobs in and out of state government. After a five-month trial, a jury in 2009 convicted the Democrat of defrauding the state Senate, a museum and a South Philadelphia nonprofit of millions.

The 3rd U.S. Circuit judges heard oral arguments as they weigh appeals by both sides.

Federal prosecutors said his sentence on 137 fraud counts should be more than 20 years under federal guidelines after enhancements they sought for complex planning and perjury. Senior U.S. District Judge Ronald Buckwalter did not rule on their motions and instead announced a 121- to 151-month guideline range, then imposed the 55-month sentence.

Circuit Judges Leonard Garth and Julio Fuentes, both of Newark, N.J., seemed to agree Wednesday with prosecution arguments that Buckwalter never explained how he arrived at those numbers.

“It sounds like a very fundamental error,” Fuentes said.

Garth similarly pressed defense lawyers to find an explanation in the record. Lawyer Samuel Buffone called it, at most, a ‘`harmless error.”

Fumo is in currently in prison in Kentucky, with an expected release date of June 2013.