BOISE, Idaho -

 Former Republican U.S. Sen. Larry Craig aims to scuttle federal campaign charges against him by arguing his infamous July 11, 2007 Minneapolis airport bathroom visit that ended in his sex-sting arrest was part of his official Senate business.

He's hoping to avoid repaying $217,000 in campaign funds the Federal Election Commission claims that Craig misused to defend himself.

Craig was sued in June by regulators, on grounds the campaign money was converted to personal use because Craig's defense in Minnesota had no connection to his campaign for federal office.

Instead, Craig's lawyer argues in U.S. District Court this week that his Minneapolis-St. Paul International Airport bathroom visit fell under his official duties.

He cites a U.S. Senate rule in which reimbursable per diem expenses include meals, lodging -- and baths.