PHILADELPHIA — A U.S. appeals court today threw out the 4½-year corruption sentence of a long-powerful former Pennsylvania state senator.

The court agreed with prosecutors that U.S. District Judge Ronald Buckwalter did not explain why he sentenced Vincent Fumo far below federal sentencing guidelines.

The court also upheld 68-year-old Fumo's conviction.

A jury in 2009 convicted Fumo of defrauding the state Senate, a museum and a South Philadelphia nonprofit of millions. The Philadelphia Democrat had been a wealthy power broker during his 30-year state Senate career. He remains at a federal prison in Kentucky.

Prosecutors had sought at least a 15-year term for Fumo, who was convicted of all 137 fraud and obstruction counts after a five-month trial, and put his guideline sentencing range at 21 to 27 years.

Fumo's sentence created a firestorm in Philadelphia and Harrisburg, especially after Buckwalter praised Fumo for his “extraordinary” public service.