Bernie Sanders and Elizabeth Warren are in a struggle to win over the progressive base. They will share the stage on the first night of the debate next week. Should we expect fireworks?
No. Their voters are actually demographically different; Sanders supporters tend to be male and poorly educated, while Warren appeals to women and the highly-educated. Second, they appear to get along pretty well. Third, while their intellectual approaches to problems are different (and that matters), their positions on the kinds of issues that will be debated are pretty much the same. As a result, their battles will be muted; Warren will probably gently remind America that she isn’t a socialist, and Bernie will make it clear that he supported Medicare-for-all before it was cool. That’s about it.
How will the left be won? Primarily through friendly pundits and surrogates, over a period of several months. In the meantime, both of them will probably go after Biden to some extent, and the real drama will come if Mayor Pete, or one of the also-rans, makes the realo case against both of them. I think that will happen; whether it will work or not remains to be seen.