Reuters: A U.S. climate change bill, already facing a difficult fight in the Senate, is facing new political problems that could sink “cap and trade” this year. A leading Senate Democrat on Tuesday said he does not think the Senate can pass a bill in 2010. A special election on Tuesday for a Massachusetts Senate seat could spell deeper problems for the long-delayed legislation. Republican state Senator Scott Brown is aiming to defeat Democratic state Attorney General Martha Coakley to …