Klaus, the voters have likely already decided. If you look at current forecast models, they predict that either Sanders wins a majority or no candidate wins a majority. And in the event that no candidate wins a majority, Sanders is most likely going to end up with a plurality. So the voters have decided.
Now the party can behave like the Republican Party in 2016 and resist. Or it can embrace the voters. In this instance, the party is going under the premise that Sandersā politics are polarizing and will lose the middle. I think the party has incorrect framing. First, there is a false idea of the left versus the middle and increasingly Sanders vs everybody, which is just an unfair comparison. Then there is this false notion that the traditionalist Democrats will just abandon the party when general elections come because moderates and socialists cannot form a coalition like the white evangelicals and the far right. Again, if you turn around the question to say how do you extend the voter base via Sanders, you get a different answer, especially after his Nevada performance.
But the problem, Klaus, is the media and moderate candidates like Manchurian Pete are conditioned to ostracize the frontrunner. So this is why the the party needs to take leadership. The convention is going to be nasty otherwise.
