Bernie Sanders at the Fox News Town Hall

To a not-insignificant number of Democrats, of course, Mr. Sanders’s populist agenda is exactly what the country needs. And he has proved his mettle, having emerged from the margins to mount a surprisingly strong challenge to Hillary Clinton, earning 13 million votes and capturing 23 primaries or caucuses.And for many Sanders supporters, the anxieties of establishment Democrats are not a concern.

That prospect is spooking establishment-aligned Democrats, some of whom are worried that his nomination could lure a third-party centrist into the field. And it is also creating tensions about what, if anything, should be done to haltR.T. Rybak, the former Minneapolis mayor who was vice chairman of the Democratic National Committee in 2016, complained bitterly about the party’s tilt toward Mrs. Clinton back then, and warned that it would backfire if his fellow mainstream Democrats “start with the idea that you’re trying to stop somebody.” Mr. Sanders.New York Times