Bernie Sanders in Politico.com

On Budget & Economy: 2012: Supported fiscal cliff compromise package on taxes

Nonetheless, two years later, he voted for a major tax and budget bill known as the fiscal cliff package, which made 98% of the Bush tax cuts permanent--a package that only eight senators opposed. It was a major compromise for Democrats, especially for Sanders, who now wants to hike tax rates to levels not seen in the last 30 years. One Democratic colleague said, "It was it a lousy deal but the only deal available."

Sanders' record of compromising doesn't make him a flip-flopper. It shows him as a pragmatist who, like most of his colleagues, compromises to pass legislation even when it may not achieve all the things he would have liked.