Most of the investigations into ACORN, the low-income advocacy group, have focused on voter registration fraud. But now lawmakers want to follow the money.

Rep. Steve King, R-Iowa, a member of the Judiciary Committee, is demanding congressional hearings into the financial structure of the Association of Community Organizations for Reform Now.

"I don't think they've been examined in any significant way at all," he said.

King questions the actions of ACORN officials as well as the multitude of nonprofit activist groups that apparently overlap with ACORN and share the same headquarters address in New Orleans.

"This spider web, this myriad web of ACORN dollars and revenue streams, every bit of them should be looked at, all the corporations that they are networked with all of the boards of directors of those corporations, the inner locking connecting, the faces that are the same from board to board."

ACORN believes an investigation of its finances is "...a continuation of the right wing Republican attacks which continues to stalk ACORN. This ACORN as 'punching bag' redundancy is not worthy of your audience."

But FOX News has found more than 250 nonprofit groups list ACORN's New Orleans headquarters as their address. Among them is Citizens Services Inc., a firm that was paid more than $800,000 by the Obama campaign for a get-out-the-vote program last year.

Citizen Services lists two ACORN headquarters as its offices and even shares a third floor legal department with ACORN.

At least two complaints that accused ACORN and one Citizen Services of violating campaign financing laws were dismissed by the Federal Election Commission.

The FEC will not comment on current cases, and while the FBI is investigating ACORN, its focus is primarily voter registration fraud.

There have been four ACORN related state prosecutions since the election, dealing with alleged voter registration fraud. None involve ACORN's finances.

But former FEC Commissioner Hans von Spakowsky says a wider probe is needed.

"ACORN has all these subsidiaries and affiliates that seem to be shell organizations with money being transferred between them and to investigate that takes a lot of resources," said von Spakovsky, a visiting legal scholar at the Heritage Foundation, a conservative think tank. "I really think that's the kind of thing that only someone like the FBI could thoroughly investigate."