The Sierra Club, one of the nation's largest and most politically-active environmental organizations, announced this evening it would endorse Sen. Barack Obama (D-Ill.) for president. The announcement was not a surprise: the group's executive director, Carl Pope, had hammered the presumptive GOP nominee, Sen. John McCain (R-Ariz.), for months over his missed votes in the Senate and his support for nuclear power subsidies as a way to address global warming. This week Pope criticized McCain for announcing he supports lifting the federal moratorium on offshore oil drilling. Tomorrow, Pope will speak at an event in Cleveland, Ohio with Leo Gerard,...