Corporate money is already financing the constant stream of political advertising in the campaign this year, but a great deal of it is undisclosed. The Citizens United Supreme Court decision opened the gates for corporations to spend directly on American elections. Now, Republic Report can offer the first look at which major corporations are fueling perhaps the biggest secret attack ad machine in U.S. history.

Leading the way among anonymous attack groups in the 2010 midterm election, the U.S. Chamber of Commerce, a lobbying association funded by multinational corporations, raised $50-75 million from its general budget to elect candidates for Congress.  Many of the ads were filled with race-baiting sleaze and blatantly false assertions, so much so that several local television stations refused to air them. Many current lawmakers owe their office to this corporate spending spree: Weeks after he defeated former Senator Russ Feingold (D-WI) with the Chamber’s help, Senator Ron Johnson (R-WI) traveled to the Chamber to personally thank the CEO and head lobbyist, Tom Donohue.

Since the Chamber has such wide sway over the composition of Congress, and the laws we must all live under, it’s worth digging into which corporations fund the Chamber. This year, the Chamber is expected to be among the top outside spending groups. In February, the group launched a $10 million attack ad volley in 20 races, mostly promoting Republican House and Senate candidates, along with Senator Joe Manchin (D-WV). By November this year, the group is expected to air many more ads.

As a 501(c)(6), the Chamber can raise unlimited corporate dollars with no disclosure, while spending much of its funds on lobbying, political advertisements, and other advocacy efforts. Without reform, we’ll never know the full picture of the Chamber’s corporate donors. But Republic Report has compiled news clips and voluntary company reports to, for the first time since the Citizens United Supreme Court decision, reveal who is bankrolling the Chamber’s attack machine:

— Coca-Cola Inc provides yearly dues between $100,000-$499,999 to the Chamber.

— American Electric Power (AEP), a large utility company, provided the Chamber with $500,000 in dues in 2010.

— Health insurance company AETNA provides $100,000 in yearly dues to the Chamber.

— eBay provides $100,000 in yearly dues to the Chamber.

— Defense contractor United Technologies provides at least $50,000 in yearly dues to the Chamber.

— Dow Chemical provided $1,648,750 in dues to the Chamber in its latest company report.

— ALCOA provides at least $25,000 a year to the Chamber.

— News Corporation, a Chamber member, gave the group at least $1 million in 2010.

— CSC, a major defense contractor and computer IT corporation, provides the Chamber with $100,000 in yearly dues.

— Eli Lilly and Company pays the Chamber at least $50,000 a year in annual dues.

— The Campbells Soup Corporation pays the Chamber at least $10,000 in regular dues.

— Prudential Financial gave the Chamber $1,057,300 in 2010, and $2 million in 2009.

— AHIP, the health insurance lobbying association that represents WellPoint, UnitedHealth, and other major insurers, gave the Chamber over $86 million in 2010. AHIP continues to fund the Chamber, but the current amount is unclear.

— Procter and Gamble is a dues-paying member of the Chamber but does not disclose the dollar amount.

— Chevron donated $500,000 to the Chamber in 2010.

— Merck, the pharmaceutical company that makes well known drugs like Clarinex and Zocor, is a dues-paying members of the Chamber that gave $725,000 in 2010.

— Microsoft provides at least $141,000 in yearly dues to the Chamber.

— Norfolk Southern Corporation spends at least $50,000 a year in dues to the Chamber.

— Xcel Energy provides at least $40,000 in dues to the Chamber.

— Xerox provides at least $25,000 to the Chamber.

— Hartford Financial Services gave $50,000 to the Chamber in 2010.

— Intel gave the Chamber $225,000, according to the most recently available company report.

— Abbot Labs Corp. is a Chamber member but does not reveal the dollar amount.

— The Chamber maintains a foreign fundraising effort to bankroll the 501(c)(6) nonprofit the group uses to run attack ads. In 2010, I reported that foreign companies like the Tata Group, the State Bank of India, and the Bahrain Petroleum Company, Bahrain Financial Harbour Holding Company collectively contribute about $885,000 to the Chamber. The Chamber acknowledged this foreign funding for its political organization, but maintains that the funds are somehow segregated from political spending.

The money these corporations give to the Chamber is intrinsically linked with the Chamber’s attack ad budget. In previous years, the Chamber used a traditional political action committee, which spent on elections using limited individual contributions, not corporate money. But now the Chamber PAC is nearly defunct — it has doled out only about $30,000 this cycle, far less than the more than $300,000 it spent a decade ago. Instead, the Chamber spends tens of millions on elections using its regular 501(c)(6) budget, not bothering to use a regulated PAC. The corporations above fund the 501(c)(6).

Why the switch from regulated individual contributions to unlimited corporate money? In 2007, the Supreme Court ruled in Wisconsin Right to Life that corporate-sponsored “electioneering communications” were allowed for issue ads. The Citizens United decision three years later knocked down the remaining barriers, and gave the power to corporations to spent unlimited amounts in support of candidates with independent expenditures. The Chamber’s shift from regulated, disclosed PACs funded with limited individual contributions to secret slush funds filled with corporate money came as a result of a big business-friendly Supreme Court.

The U.S. Chamber of Chamber, which maintains little to no connection with most local chambers of commerce, selects candidates based in part by a scoring system of policy issues. The Chamber’s policy website lists its policy positions on their website, including votes they “score.” The Chamber asks candidates to oppose oil speculation regulations, support the bank bailouts, oppose health reform and the public option, support corporate tax cuts, support unfettered free trade, and other big business prerogatives. Recently, the Chamber has pushed controversial Internet censorship legislation, the Stop Online Piracy Act (SOPA).

For this election cycle, the Chamber hired a corporate lobbyist named Scott Reed to head up their advertising and political strategy. Reed’s specialty? Using corporate front groups to smear politicians who support regulations on big banks, health insurers, and other large companies.