Ehh, I think there was an organized effort to stop Bernie, more or less, and those endorsements were a big part of it. And it worked. Bernie's campaign didn't think it would work, even made fun of the establishment for trying. But it worked. https://twitter.com/Robillard/status/1247214315557597185

The questions are 1) why did such an effort take place? and 2) why did it work? And I think the Sanders campaign has a lot of thinking to do about how much of an us vs. them mentality it had, and it's lack of work in building alliances across the party.

It also shouldn't be surprising it worked. For years the evidence was on the side of the nomination being a coalition-building exercise that punishes factional candidates. Bernie gambled on Trump 16 being a new normal. They were wrong; it was the exception to the rule.