PHILADELPHIA — A long-powerful Pennsylvania senator appeared haggard as he returned from prison Wednesday to be resentenced in a sprawling corruption case.

Vincent Fumo, 68, a Philadelphia Democrat, is halfway through a 4Z\x-year prison stint, but could get a much longer term when his sentence is recalculated today.

Prosecutors are again seeking a 17- to 22-year guideline sentence after an appeals court threw out a federal judge’s sentence. Fumo hopes to keep his below-guideline sentence because of his medical ailments and advanced age.

Fumo entered the packed courtroom Wednesday sporting a green jumpsuit and a shock of shaggy white hair. He also has a white beard, ashen skin and a slight facial tic. He has been incarcerated at a federal prison in Ashland, Ky.

A wealthy banker and lawyer, he was one of the most powerful political figures of the past generation in Pennsylvania. During a 30-year Senate career, he controlled the Senate Appropriations Committee for a time and authored key legislation.

A jury in 2009 found that he also used his power to defraud the state Senate, a museum and a neighborhood nonprofit of millions. He used Senate staff for constant personal and political chores, from cleaning his mansion to spying on rivals to driving a car to Martha’s Vineyard, Mass., as he sailed for free on a museum yacht. He was also convicted of obstruction.

Prosecutors offered testimony Wednesday to suggest the much-debated sentence had further eroded the public’s confidence in government.

“The period of time over which it occurred makes it appear that the activity was almost institutionalized,” John J. Contino, executive director of the Pennsylvania State Ethics Commission, testified Wednesday. “Democracy’s a victim here.”