With his penchant for sweater vests and stories about his coal miner grandfather, former Sen. Rick Santorum is setting himself up as the populist conservative alternative to Mitt Romney, the millionaire GOP presidential frontrunner who bested him by a mere eight votes in Tuesday's Iowa caucuses.

"I share the values of the working people," Santorum said in his speech to Iowa supporters as the caucus results were being tabulated.

But while Santorum has crafted a folksy image for his presidential campaign, the Sunlight Foundation's Influence Explorer suggests a different picture. Retirees make up the largest sector of Santorum's financial support, perhaps not surprising for a politician who represented a state that ranks fourth in the nation in percentage of senior citizens.

As a 16-year congressional veteran however, he has also relied on means of support traditionally favored by Washington politicians: large legal firms and financiers.

Lawyers and employees from law firms have donated $2 million to the former senator; the securities and investment sector, insurance sector, health care professionals and the real estate sector each ponied up $1 million or more. 

In the course of his political career, which began with his 1990 election to the House, Santorum's top contributor has been Federated Investors Inc,  a Pittsburgh investment firm that manages an estimated $299 billion in assets and has a history of donating to Pennsylvania politicians.  Over Santorum’s career Federated Investors PAC and employees have contributed $164,500 to Santorum, more than any other single politician.

Santorum’s second top career contributor is the lobbying empire, Blank Rome. Their PAC and employees contributed $144,400 to Santorum’s various campaigns. Some of Blank Rome’s notable clients include, Comcast and Prudential Financial and several U.S. municipalities, including the City of Philadelphia.  

Kirkpatrick & Lockhart, the former incarnation of the international legal giant K&L Gates, contributed a total of $109,900 to Santorum’s campaigns. The firm and its employees have given significantly less to Santorum since making the jump from a Pittsburgh-based law firm to an international conglomerate. 

As a presidential candidate, Santorum has picked up the most financial support from employees of Blue Cross/ Blue Shield, Diamond Manufacturing Company (a perforated metal company in Pennsylvania), and Northwestern Mutual.