Where does the Chamber of Commerce get its money?

From membership fees by small businesses?   Well, not exactly...

The U.S. Chamber of Commerce astonished even the most jaded Washington-watchers last year when it reported spending nearly $150 million on lobbying. The figure obliterated all previous records and cemented the chamber's reputation as Capitol Hill's most formidable lobbying force.

But it turns out that a lot of that money came from an injection of funds from another lobbying powerhouse: America's Health Insurance Plans.

The private insurers' group gave $86.2 million toward the chamber's media and lobbying blitz against President Obama's health-care legislation in 2009 even as it was pledging general support for the idea of reform, according to tax records and sources familiar with the gift.

The donation made AHIP the chamber's single largest funder in 2009, accounting for about 40 percent of the business lobby's $205 million in contributions that year, records show. 

The rest of the story is at the Washington Post link.