John McCain wants to know whether Barack Obama is going to accept public funding if he's the Democratic nominee.

Obama's other option would be to use his prolific fundraising operation.

Campaigning Saturday in Wisconsin, McCain said he'd made his own commitment to accept public financing for the fall campaign. And he says he wants to know if Obama is going to keep his own commitment.

But the Obama camp says there's no such commitment. A spokesman calls public financing "an option that we wanted on the table," but adds that there's "no pledge" to take the public money and the spending limitations that come with it.

Obama told reporters that if he's the nominee, his campaign will talk to McCain's campaign about abiding by the rules of the general election.