Big money can throw its weight around even more effectively in congressional races.
"Five million spent in the presidential race, it's a lot of money to me, but not a lot of money out of the total spent in the election," former FEC chief Potter said. "You take the same $5 million and you spend it in a House race and you're spending more than everybody else combined. You'd be the single largest spender in most Senate races.
"It is possible to buy, or try to buy, a House or Senate race through this anonymous money and nobody will know you're doing it," he said.
The Republican-allied Chamber of Commerce promises an unprecedented effort this year after spending more than $30 million on the 2010 midterms, just after the courts opened the door. Other groups are piling on, too. Both Democratic and Republican leaders have started super PACs in their fight for House and Senate control.
Many of the donors will be familiar. The House Republican group already has received $5 million from Gingrich's super givers, the Adelsons.
Associated Press writer Jack Gillum contributed to this report.