Jay Cost examines the truism that competing opinions among Democrats will sabotage the party in November, and finds it wanting.
His last graph sums it up rather nicely.
Generally speaking, the “division means defeat” argument does not operationalize very well. It is one thing to claim it in the abstract, as so many do. It is another thing altogether to explain how it actually works. Which candidates are harmed by Democratic pluralism, how are they harmed, why are they harmed? These are the questions that need to be answered, and answered with specificity, for this presumption to stand. I do not think there the answers are sufficient. “Disunity means defeat” is one of those arguments that seems intuitive in the abstract, but upon closer inspection makes little sense in a candidate-centered age of politics.