U.S. Sen. Rick Santorum's re-election campaign said the incumbent Republican would release his tax returns only if his opponent, Democratic state Treasurer Bob Casey, agreed to release his public schedule for the past year.

At their debate in Philadelphia Monday, Mr. Casey challenged Mr. Santorum to release the tax data. Mr. Santorum immediately agreed. He noted that it might take some time to assemble the paperwork but placed no conditions on the promised disclosure at the time.

His campaign press secretary, Virginia Davis, said yesterday that the tax returns were now ready for release. She offered to allow reporters to examine them privately, but insisted that the tax data would not be released for publication until Mr. Casey agreed to disclose his public schedule for the last year.

"If he is not going to release his tax returns, then he clearly lied Monday night in the debate and he reneged on his pledge that he made Monday night to the people of Pennsylvania,'' said Larry Smar, Mr. Casey's press secretary. "What is Rick Santorum trying to hide?

"As to our public schedule, he can read the newspapers,'' Mr. Smar added. "By definition, public schedule is public."

Mr. Smar also took the opportunity to revisit the Casey campaign's previous criticism of Mr. Santorum for failing to release records of a charity that he formed, which at times employed members of his campaign staff.

The Republican campaign is hoping to smoke out information to buttress its claim that Mr. Casey doesn't punch the Treasury Department clock as often as he should. The incumbent has hammered at the issue since The Philadelphia Inquirer reported early this year that Mr. Casey had been away from his Harrisburg office campaigning and fund raising on more than half the working days of his first year as treasurer.

Ms. Davis said the Santorum camp believes the Casey schedules would show that he continued to spend much of his time away from his official duties. She also said she was skeptical of his claim, in answer to a question from Mr. Santorum, that he had visited each of the state's 67 counties.

"What I've read in the papers tells a story of Mr. Casey blowing off work and avoiding public events as often as possible,'' Ms. Davis said in an e-mail that cited the Inquirer article and others suggesting that the Democrat was maintaining a relatively light campaign schedule -- a characterization that Mr. Casey has rejected.

"The voters of this state deserve to know if Mr. Casey really wants this job, and if two campaign events a week are any indication, he doesn't want it at all,'' she said.

Ms. Davis sidestepped questions on the Casey campaign's call for fuller disclosure of the spending records of the Santorum charity.

"Right now, this is what we're focusing on,'' she said, referring to the schedule information.

Mr. Casey released five years of income tax returns yesterday. They showed his government salary accounted for the bulk of his income. His 2005 return showed an adjusted net income of $121,104. Following Senate rules, Mr. Santorum has made annual disclosures of his financial interests, but those disclosures report income in broad ranges and lack the specific data of tax returns.