He is trying to catch the moderate voters, Dem. voters who don't follow politics closely. When he build up the base he will return to the Dems. as the person who reform the party for the good.
Sadly the moderates are the #Walkaway.
I saw this tactic in my country, don't worry Anon it never works, because it is too late.
If you think about it could be a nice plan. Running the old fuck Bernie in 2020, and put your Depstate man as VP. When Bernie wins got sick, got a heart attack or somethnig. Than put your VP in his place. He is old, seems legit.
But we all know they have already lost 2020.
Don't be surprised they will pull these things until their last breath.