From Greg Sargent's The Plum Line blog:

Castellanos' Firm Also Has Contract With U.S. Chamber Of Commerce

One of Castellanos' firms, as you know, was the ad buyer behind a major insurance industry TV campaign against health care reform. His firm also has raked in nearly $500,000 from the Republican National Committee, which enlisted him to craft anti-reform talking points.

Here's one more interesting data point: Another one of his firms, Purple Strategies, also has a contract with the U.S. Chamber of Commerce, one of the most determined and well-funded foes of Obama's governing agenda.

J.P. Fielder, the Chamber's spokesperson, confirms that Castellanos' firm is doing the advertising on the Chamber's ongoing multi-million-dollar campaign hailing the virtues of the free-market system - which has the specific goals of derailing Obama's climate change and health care reform initiatives.

To be clear, there's nothing necessarily amiss here, and I wanted to take this occasion to clarify something. The reason we're digging into Castellanos is not because of Castellanos per se, but because his case tells a larger story about how Washington works. You hear a lot about the revolving door between government and lobbying. But there's another, less-remarked-on revolving door: One between consulting and commentary.

Previously:

Sargent: CNN Admits That On-Air Commentator Worked For Insurance Industry, Promises Full Disclosure

CNN's Castellanos' firm is ad buyer for AHIP's anti-health care ad blitz