The group is a non-partisan, but left-leaning, organization that reviews and analyzes the Congressional voting database for you. You can check each vote of your Congresscritter and see if it matched the progressive position at the time. The votes are even broken out into handy-dandy categories for you, such as Housing, Corporate Subsidies, War and Peace, Family Planning, and so on. Nifty!
Since it is common wisdom among many progressives that Hillary has a very conservative voting record, I looked it up. Believe it or not, she has a 91.29% rating overall, making her the 16th most progressive Senator in Congress. I also checked Senator Obama's record. Surprisingly, his rating is a bit lower - 88.76% - making him the 24th most progressive Senator in Congress.
Of course, it also works for your personal CongressPeople. I just checked out my Representative, Nita Lowey, and let's just say if a Progressive Democrat challenges her in the primaries, I'm not voting for the incumbent. War and Peace at 66%! Yikes!
But don't believe me. Go check it out for yourself, and maybe give them a little turkee for making it so easy to fact-check our Critters' Creds!