Billionaires, shadowy groups fuel pricey election

At the presidential level, both Obama and Romney have spent considerable time at fundraising events courting wealthy donors. Romney last month lamented the time he spent on fundraising, rather than speaking to larger groups of voters.

Obama and Romney have raised considerable money from small donors, too, especially the president's legion of more than 4 million donors. Still, individual donations of $20 or even $50 are dwarfed by money from Las Vegas casino mogul Sheldon Adelson — the top super PAC donor this year — who contributed more than $40 million to Republican super PACs, including those backing Romney and former candidate and House Speaker Newt Gingrich. For Obama, high-profile figures like Hollywood producer Jeffrey Katzenberg have donated millions of dollars to super PACs supporting him.

Federal rules require timely disclosure for super PACs, but determining who's behind big donations isn't always easy. In summer 2011, a fledgling company dissolved shortly after making a $1 million contribution to a super PAC supporting Romney. Records showed that the company, established and closed over a four-month period, was formed by Ed Conard, a Romney supporter who once worked with the former Massachusetts governor at the private equity firm Bain Capital.

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