Politico: A handful of swing-state Democrats hold the cards when it comes to blocking the Obama administration’s climate change policies. At least 56 senators next year are likely to support efforts to block the Environmental Protection Agency’s plans to regulate greenhouse gas emissions, a POLITICO analysis shows. That’s just short of the 60 they’d need to overcome a filibuster, but a slew of moderate Democrats facing re-election in 2012 could put that number within reach. Democratic senators including…