San Francisco Chronicle: Environmentalists celebrated earlier this month when a key House committee approved a contentious proposal to combat climate change after months of often-bitter public deliberations and intense closed-door negotiations. But for congressional supporters of the bill, the really hard part is just beginning. To get the climate change initiative to the House floor – and ultimately passed by the chamber – Speaker Nancy Pelosi, D-San Francisco, and Rep. Henry Waxman, D-Los Angeles, …