Maine Sen. Olympia Snowe
Almost more than any other senator, Mainer Olympia Snowe is known to work and vote across party lines. Regularly labeled a RINO (Republican in Name Only) by more conservative Republicans, Snowe enjoys an incredibly strong base of local support (she won her last election by nearly 40 percentage points) and doesn't have much to worry about when the likes of Sean Hannity and Glenn Beck call for her electoral scalp.
Snowe received a 91 percent score from the League of Conservation Votes and in 2006 called on ExxonMobil to stop funding groups that spread fear, uncertainty and doubt about the science of climate change. In 2007, she co-sponsed the Global Warming Reduction Act of 2007 with Massachusetts Sen. John Kerry, a bill that would establish a cap-and-trade program to fund the transition to clean energy technology.