U.S. Sen. Rick Santorum's campaign manager accused state Treasurer Bob Casey of hypocrisy in questioning the circumstances of a Santorum home loan when Mr. Casey had also secured a mortgage from an institution whose officers were contributors to his campaigns.

"On attack after attack against Rick Santorum, Bob Casey Jr. shows that he is an enormous hypocrite,'' Vince Galko, the Republican's campaign manager, said in a statement.

The back-and-forth over home loans started with articles in The American Prospect and the Philadelphia Daily News, which raised questions about the fact that Mr. Santorum had received a mortgage on his Virginia home from a Philadelphia financial institution that normally provides mortgages only to affluent customers of its overall investment services.

Mr. Casey contends the reports raised questions about the possibility that the senator had received preferential treatment on the $500,000 refinancing of his Leesburg home. Mr. Casey released information on his own mortgage, for $120,000 from a Scranton bank.

Neither side has said their opponent received clear financial benefit from the terms of their mortgage.

The Santorum campaign, however, seized on reports that the officers of Mr. Casey's bank had been contributors to his campaign, contending that it was evidence of the partisan motive of his earlier criticism.

Larry Smar, Mr. Casey's campaign press secretary, acknowledged that he couldn't point to any specific financial break in the terms of the Santorum loan, but he echoed the original articles in questioning the loan's source.

"The fundamental difference here is that Rick Santorum went to a private bank and got some kind of special deal that wasn't available to the general public,'' Mr. Smar argued. "Our main contention is that this is a private bank and that a door was opened up somehow."

Mr. Casey and Mr. Santorum appear to be headed toward one of the most expensive and closely watched U.S. Senate races in the country this November, although both face opposition in the May primary.

Also vying for the Democratic nomination are Chuck Pennacchio, a history professor, and Alan Sandals, a lawyer. Businessman John Featherman is seeking the GOP nomination.