Biden will need the support of the Bernie Bros in the general election if, as expected, he is the nominee. How can he campaign against Sanders without offending them?
One way is to use Bernie’s own words against him. The obvious choice is “revolution.” That doesn’t sound too appealing to the elderly and swing voters, but it is the essence of the Sanders campaign. Bernie can hardly disown it at this point. Just say in a matter-of-fact way that you are in favor of incremental reforms, while your opponent wants a “revolution,” and the moderate case practically makes itself.