Nice try on the "disentangling," but I am not interested in being your research assistant. I am refusing the premise of the question because it is a pivot designed to move the goalposts. Whether or not I provide a list of names that meets your criteria has no bearing on the actual point. You have constructed an absurdly narrow set of qualities where a person must be "left-wing" and must be an "elected official" and must be on the "Democratic ticket" all to avoid the reality of what is happening in this thread. Donal is currently doing the exact thing he claims is a strategy for failure. He is attacking a Democratic faction and repeating right-wing talking points while claiming to be "just a guy" with no impact.
If your argument is that this behavior is destructive when a "moderate" does it, then you have to explain why it is not destructive when you do it. Demanding I find examples that fit into your specific, tiny box is just a way to avoid answering for your own actions. I am interested in the actual results of the choices being made here, not in going on a wild goose chase to satisfy a distraction.