Dems who have known Sanders for decades are aware he is often unwilling to compromise.

“Senator Sanders understands what it takes to get legislation across the goal line.” – Richard Burr (R)

“Negotiating with Bernie was not a usual experience, because he is very passionate and he and I are both very strong-willed people and we spend a lot of time banging our fists on the table, and having the occasional four-letter word…But at the end of the day, Bernie was result-oriented.” – John McCain (R)

“Last year when we had the scandal at the VA, he was incredibly effective, engaged in getting the legislation passed, in getting it funded. Frankly, without him, I don’t think we would have gotten it done because there was a lot of name-calling, but there wasn’t a lot of constructive, ‘OK, here’s the resources. …’ And he did it. And it was a great testament to his skill as a legislator.” – Jack Reed (D)

“He would call them ‘tripartite amendments’ because we’d have him and he’d get a Republican, he’d get a Democrat and he’d pass things. He’s good at building coalitions.” - Sherrod Brown (D)

“I learned early on not to be automatically dismissive of a Bernie Sanders initiative or amendment." - Roger Wicker (R)

"But he was an honest liberal. I’ve worked with people who tell you they are going to do one thing and then do another, and Bernie did what he said. And he was very effective. It was the first real reform of the V.A. ever.” - John McCain (R)

“Bernie and I worked very well together for the betterment of the town. We were the odd couple.” - Tony Pomerleau, prominent developer and Republican in Burlington, who initially opposed Bernie's mayorship