NEW YORK (Fortune) -- An influential coalition of Fortune 500 companies and environmental groups that was formed to support climate-change legislation has splintered over the Lieberman-Warner bill that is headed next week to the Senate floor. The U.S. Climate Action Partnership formed last year won't take a position on the bill, although nine of its members - including General Electric (GE, Fortune 500), Alcoa (AA, Fortune 500) and four utility companies - signed a letter to senators backing the legislation. The letter, also signed by big environmental groups and obtained by Fortune, says: "Prompt action on climate change is essential...