I’ve been saying that for a while about Biden being the nominee.
They’re waiting until after the primaries are over to do as much as they can to deny Sanders any sort of a claim on the nomination and allow Hillary’s delegates to be moved to Biden.
Chances are excellent Warren will be his running mate, which will pull back most of the Sanders support.
And Biden’s slogan can be: If you liked the socialism and government of Uncle Joe Stalin, then vote for Uncle Joe Biden.