There really isn't even that much to say at this point. Although Biden's surge in the polls has been remarkably fast, this is not a terribly close primary at this point -- it's much less close than it was in 2016, which wasn't that close -- and there's no indication that it's getting closer. Biden's support is quite geographically robust, and even if there were a massive shift back toward Sanders, we're at the point where it might be coming too late. If the states set to vote over the next two weeks were good ones for Sanders, that might leave at least a little bit of an opening. But instead, this is one of the worst stretches of the calendar for him. He's going to lose a lot of delegates in Florida and Georgia, in particular.