Washington (CNN) -- Flooding the airwaves this election year in battleground states across the country are Democratic ads featuring two men not on any ballot, and not even politicians.

They're the Koch brothers, billionaire businessmen and GOP mega donors.

Senate Majority Leader Harry Reid takes the unusual step of regularly ripping Charles and David Koch from the Senate floor. He says they have "no conscience," calling them "un-American." And now, is proposing a constitutional amendment to ban the kind of anonymous political giving the Kochs engage in and, some experts say, perfected.

Other high-profile Democrats are hitting the Kochs, too -- from Vice President Joe Biden to former Vice President Al Gore, who this week argued Republicans are reluctant to publicly accept the existence of man-made global warming for fear of crossing the Koch brothers.

"I don't think it's particularly complicated. They will face primary opponents financed by the Koch brothers and others who are part of their group," Gore said.

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Democratic sources tell CNN it's a carefully crafted strategy to make the Koch brothers the 2014 election villains -- the personification of the rich manipulating the political system -- bankrolling a GOP agenda to get richer.