Unfortunately, because the Sanders campaign has attacked Biden on multiple fronts, Bernie's supporters are becoming increasingly *negative about Biden*.
The longer Bernie stays, the more long-term damage to Biden's candidacy.
When Bernie DOES decide to hang it up (and let's hope that's soon), he needs to somehow UNDO the negativity he has caused his supporters to have toward Joe Biden.
nytimes.com/2016/06/13/us/…