The Government Integrity Fund Action Network, a Columbus, Ohio-based super PAC that dropped a late $1.1 million ad buy opposing Connecticut House candidate Elizabeth Esty last week, disclosed today the big donors who funded it: A pair of political nonprofits that don't disclose their donors.

New Models LLC contributed $627,000, while the Government Integrity Fund, a nonprofit sister organization of the super PAC, gave $475,000. Because both New Models and the Government Integrity Fund are social welfare organizations, they are not required to disclose their donors.

The three groups show why, in the post-Citizens United world of campaign finance, not even Sam Spade could follow the money.

New Models LLC first surfaced in 2010, contributing $250,000 to a super PAC, Citizens for a Working America PAC, for a late $250,000 ad buy attacking Rep. John Spratt, D-S.C., then the chairman of the House Budget Committee. Spratt, who'd held his seat for 28 years, lost his race.

In the summer of 2011, Citizens for a Working America made the news again when reports surfaced that the group planned to throw its support behind the presidential campaign of Rep. Michele Bachmann, R-Minn., who had just won the Iowa straw poll. But that support never materialized and just before Christmas, Citizens for a Working America Inc., a social welfare organization that doesn't have to report donors, plunked down $475,000 to help Bachmann's Republican presidential rival, Mitt Romney, in Iowa.

The following month, Citizens for a Working America PAC spent $455,000 on behalf of GOP presidential candidate Mitt Romney, who was then locked in a battle with former House Speaker Newt Gingrich in the South Carolina primary. The source of that money was a pair of social welfare organizations: Citizens for a Working America Inc. and New Models. 

The Government Integrity Fund Action Network is just as shadowy. On ad buy disclosures filed by a Hartford, Conn., television station, the super PAC lists its treasurer, William Todd, as its only officer. Organizations are supposed to disclose their controlling officers when they buy air time. A Democratic political blog in Ohio has identified Todd as a Columbus lawyer who once ran unsuccessfully against the city's Democratic mayor, Michael Coleman.

Todd, contacted last week, told Sunlight he is the only officer in the organization. Asked who made the decisions about what races to intervene in and where to spend money, he said that political consultants do that. "I talk to Tom Norris," he said.

Pro Publica reported that Norris is a state lobbyist who hired a former aide to Josh Mandel, Ohio's Republican state treasurer who's currently running for Senate against incumbent Sherrod Brown. State filings by the Government Integrity list Norris as the chairman and CEO of the Government Integrity Fund. The social welfare organization has spent more than $1 million attacking Brown and supporting Mandel.

It's allied super PAC, the Government Integrity Fund Action Network, spent $1.1 million on ad buys in early October opposing Democratic candidate Esty in Connecticut's 5th congressional district. Esty is facing off against Republican Andrew Roraback for an open seat. Incumbent Rep. Chris Murphy, a Democrat, is running for Senate.