I think the state of the race would also just not need to be as bad for Sanders as it currently appears, and I'll start there
Well here's something to mull: the three biggest swings/errors that I can remember in Dem primaries came after a candidate posted a decisive win that threatened to allow them to run away with the race (NH08, MI16, SC/ST20). Voters put on the breaks.
I think it's obvious it's overwhelmingly shift, to be clear. But if it's 15% compositional, that helps Bernie a lot v. 0%
This would be really important, since it's why we assume Biden's up big in MI