Campaign finance watchdog groups filed a complaint Wednesday with the Federal Election Commission alleging that Rick Santorum's presidential campaign illegally directed a donation to a super PAC.

The complaint is based on a Sunlight Foundation report in which Louisiana mega donor Bill Doré recounted how he was instructed to donate $1 million to the Red, White and Blue Fund, the super PAC supporting Santorum's 2012 run for the presidency. It comes days after Santorum triggered speculation about an encore presidential run with a visit to Iowa, the state that will kick off the 2016 campaign with its much-watched ...