The fallout—make that dropout—continues to build over the U.S. Chamber of Commerce’s ridiculous call for a show trial on global warming.

You may recall that last month the Chamber, the nation’s leading business lobby with 3 million members, challenged the EPA to conduct a public hearing examining the scientific evidence for man-made climate change. Chamber execs said it would be "the Scopes monkey trial of the 21st century" — a rather unfortunate analogy, as they later admitted, if the group was hoping to be seen as appealing to reason. The Chamber furiously backpedalled, denying they were global warming deniers, but the cat was out of the bag. (The chimp was out of the cage?)

Last week Pacific Gas & Electric Co. of San Francisco resigned from the Chamber, blasting its "extreme rhetoric and obstructionist tactics":

We find it dismaying that the Chamber neglects the indisputable fact that a decisive majority of experts have said the data on global warming are compelling and point to a threat that cannot be ignored… Intellectually honest argument over the best policy response to the challenges of climate change is one thing; disingenuous attempts to diminish or distort the reality of those challenges are quite another.

Now PG&E’s been joined in quitting the deniers club by PNM Resources, an Albuquerque, N.M., electric utility, as well as Exelon, a power company that operates the country’s largest fleet of nuclear reactors. PNM’s spokesman said:

We see climate change as the most pressing environmental and economic issue of our time… We have decided that we can be most productive by working with organizations that share our view on the need for thoughtful, reasonable climate change legislation and want to push that agenda forward in Congress.

Nike is also among the businesses expressing its dismay over the Chamber’s know-nothing stance, although the Oregon shoe company hasn’t said if it will quit the group.

UPDATE, Sept. 29: Today the Chamber of Commerce issued a statement again denying that they don’t believe in global warming. They say they just want to make sure that saving the planet doesn’t come before making money.

UPDATE 2, Sept. 30: Nike’s chairman has resigned his position on the Chamber’s board of directors, although the company has not pulled its membership.