In a surprising move, Richard A. Sprague and his firm asked today for permission to withdraw as lawyers for indicted state Sen. Vincent J. Fumo (D., Phila.).

The request comes just three weeks after U.S. District Judge William Yohn ruled that Sprague and his firm, Sprague & Sprague, could represent Fumo, despite conflicts of interests alleged by prosecutors, as long as Fumo waived and acknowledged any such conflicts in court. Yohn had set such a hearing for later this month.

Instead, Sprague and colleagues Mark Sheppard and Geoffrey Johnson filed a motion this morning, seeking to withdraw.

"There exists good cause for seeking to withdraw," the motion said.

The motion did not state a reason, though lawyers who withdraw from cases routinely do not state a public reason, citing lawyer-client confidentiality.

Sheppard declined to comment.

Assistant U.S. Attorney Robert Zauzmer said: "We approve. We filed a motion for disqualification based on conflicts of interest."

Fumo faces 139 federal charges of fraud and obstruction of justice.

He is charged with using Senate employees to perform personal and political tasks and with defrauding Citizens' Alliance on a grand scale - allegedly using more than $1 million of its money to furnish homes that he keeps in the city, at the Shore, and on a farm near Harrisburg.

He is also charged with defrauding the Independence Seaport Museum and with obstruction of justice for allegedly trying to thwart the FBI and IRS investigation by engaging in a cover-up.

Fumo has said that he is innocent and that the indictment is politically inspired by Republicans at the Justice Department. He resigned from several key government posts after his indictment, but remains one of the state's most influential senators.

During the four-year federal investigation, Sprague and his law firm represented not only Fumo, but also three entities that prosecutors ultimately labeled as victims of the senator's alleged crimes: the state Senate and two nonprofits, Citizens' Alliance for Better Neighborhoods and the Independence Seaport Museum.

Sprague and Fumo are longtime friends.

In a 54-page ruling last month, Yohn said that "these conflicts can be cured . . . and do not overcome the constitutionally mandated presumption that a defendant is entitled to counsel of choice."

Three former Fumo aides - Ruth Arnao, Mark C. Eister and Leonard P. Luchko - are also charged.