InsideClimate: In the latest show of force by opponents of the Keystone XL pipeline, a group of 150 major Democratic donors sent a letter Friday to President Obama, urging him to reject the controversial application from TransCanada for permission to send more than 800,000 barrels of tar sands oil a day from Alberta to the Texas Gulf Coast. The signatories comprise business leaders, philanthropists and celebritiesincluding clean energy entrepreneurs Vinod Khosla, Jigar Shah and Steve Kirsch, long-time Obama bundler...