(Photo credit: Flickr user Brian Harrington Spier)

Last week, we told you how the U.S. Chamber of Commerce — perhaps the most powerful corporate lobbying group in all of Washington — is spending hundreds of thousands of dollars to launch mailers in Massachusetts attacking Elizabeth Warren.

It’s important to remember that even though the Chamber has “U.S.” in front of it’s name, it has been caught in the past taking funding from foreign entities like the state-owned Bahrain Petroleum Company.

Because it refuses to disclose its donors, we don’t know who all of the group’s corporate sponsors are. But an alarming bit of news from the Wall Street Journal suggests that they may be even more corrupt than we imagine. The paper reports that the Chamber is suing to stop regulations that require companies to disclose whether they use blood diamonds:

The U.S. Chamber of Commerce and the National Association of Manufacturers filed a challenge late Friday toAi??rules requiring U.S.-listed companies to disclose whether their products contain minerals blamed for fueling violence in central Africa.

The Chamber works on behalf of its donors, and this bit of news suggests that companies involved in the blood diamond trade in Africa are likely Chamber donors.

Members of Congress work on behalf of their donors, too. The Chamber opposes the Affordable Care Act and equal pay for women. So does Warren’s opponent, Sen. Scott Brown (R-MA).

If Brown is re-elected with the Chamber’s dollars, we may see him, too, fighting regulations requiring the disclosure of blood diamonds.

We don’t have to let that happen. Click here to sign up make calls to voters for Warren.