WASHINGTON - Exelon Corp, the largest nuclear power operator in the United States, on Monday became the latest U.S. power company to say it will leave the Chamber of Commerce over that group's opposition to the climate bill.

The Chamber and other groups think climate legislation will be bad for the economy, an Exelon spokeswoman said. We think it's going to be good for the economy.

Exelon's top executive John Rowe said in a speech on Monday that the company would not renew its membership in the Chamber, which has pushed for public hearings to challenge the scientific evidence for man-made climate change.

Nuclear power is virtually emissions free, which means Exelon could face less emissions costs under climate regulation than a utility that generates electricity mostly from coal and natural gas.

Exelon followed California utility PG&E Corp and New Mexico based PNM Resources Inc in leaving the chamber over the dispute.

Democratic Sens. Barbara Boxer and John Kerry are slated to introduce the Senate's version of the climate bill on Wednesday. Climate legislation passed narrowly in the House of Representatives in June.

Inaction on climate is not an option, Rowe said in the speech. If Congress does not act, the (Environmental Protection Agency) will, and the result will be more arbitrary, more expensive, and more uncertain for investors and the industry than a reasonable, market-based legislative solution.

(Reporting by Timothy Gardner; Editing by David Gregorio)

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