However as I and others have pointed out, Sanders supporters are far less likely to change their minds. Which may give them a certain persuasiveness in a caucus where there are already a lot of them, to begin with. Unlike many other candidates, Sanderss support can only grow.

That's true of all of the top candidates. Sanders's supporters aren't the only ones who strongly support their candidate or can convince others to switch. Sanders is not unique in that, nor are his supporters.