Still, an individual giving millions of bucks to influence an election, which is happening right now in the presidential race, is just as problematic as money that pours in from unions and corporations, reform groups say.
"We are also very concerned with individuals making huge donations," said Mary Boyle, a spokesperson for Common Cause, which is leading an effort to repeal the Supreme Court's Citizens United decision. A single person or industry shouldn't be able to buy influence or access, Boyle said.
And the watchdogs argue that corporations and other organizations are likely donating to 501(c)(4) groups that do not have to disclose their donors.
"They want all the benefits of influence-buying money, but they don't want the public scrutiny," said Paul Ryan, an attorney at the Campaign Legal Center.
Certain groups have both Super PAC and nonprofit arms to attract as many donors as possible, but there are limits on how much the nonprofits can spend bankrolling political activities -- restrictions the Sunlight Foundation's Bill Allison called the "the price to pay for secrecy."
Another reason individual donations are outpacing organizational contributions to presidential Super PACs is that businesses and unions have historically been more focused on congressional elections and party giving, Allison said.
"It's been an individual's game until this point," he said.
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