Think Progress:

Today, Exelon CEO John Rowe announced that his company — the largest electric utility company in the United States — would not renew its membership in the U.S. Chamber of Commerce because of its opposition to global warming action. In his keynote address to the annual conference of the American Council for an Energy-Efficient Economy (ACEEE), the nation’s largest association of energy efficiency experts, Rowe said that the Chamber’s multi-million-dollar campaign against clean energy legislation is incompatible with Exelon’s commitment to climate change leadership.

Here is Exelon’s full statement (h/t Pete Altman an NRDC):

Rowe ACEE _Chamber Announcement_ Speech –