Just when you thought you had the shadowy world of super PACs figured out, here comes a new twist: Three big Democratic super PACs — formed to support President Barack Obama, and House and Senate Democrats — are banding together to form the first ever joint fundraising super PAC.

The three, which registered their joint committee with the Federal Election Commission last week, are among the largest super PACs, in terms of contributions to their committees. They've raised a combined $10 million for the 2012 election so far. But that figure looks less impressive when compared with the haul of some of the GOP competition. So now, through a fund called Unity 2012, the Democratic super PACs will have another, and perhaps more convenient, way to raise dough. Call it a super-duper PAC.

"This is a vehicle for donors who want to participate in more than one progressive group," Bill Burton, the former White House deputy communications director who founded the Obama-supporting Priorities USA Action, told the Wall Street Journal in unveiling Unity 2012. He could not be reached for further comment.

Joint fundraising committees are common among regular PACs, which face contribution limits. But no one, including Unity 2012, has ever formally asked the FEC whether super PACs — which came into existence after the Supreme Court's 2010 Citizens United ruling and can raise unlimited funds — could join together. 

The possibilities for coordination and special deals among super PACs seem limitless. Hundreds of super PACs have formed in the past two years. Since last year, 23 hybrid PACs, regular PACs with a separate super PAC account, have formed, resulting from the lawsuit Carey v. FEC. Now other super PACs may decide to band together like the Democratic groups have.

It's unclear how the funds will be divvied up among the three groups behind Unity 2012: Priorities USA Action, House Majority PAC (aimed at electing House Democrats) and Majority PAC (to elect Democrats to the Senate). In its fundraising solicitations, the group must inform its donors what percentage goes to each. 

Diana Rogalle is Unity 2012's treasurer. She is the former finance director of the Democratic Senatorial Campaign Committee who now leads a fundraising consultancy called the Ashmead Group. She is also a senior advisor to Priorities USA Action, Burton told the Wall Street Journal.