Oh, something I wanted to mention in my other post about the CNN poll but I didn't get to because my one kid was throwing a fit....
Bernie's been incredibly static. He doesn't fluctuate much. He's not gaining anything, but he's not really losing anything either. I really do think his floor and ceiling basically touch at this point. As long as he's in the race, he's going to have that 10-15% of folks who are ride or die. I don't know if viability matters to these folks or not. Warren, on the other hand, has shown an increase but she's doing it fairly steadily. She's not gaining and then losing ground like Harris has done. That leads me to believe she's locking in some support long term which bodes well.
Biden's support is interesting in that it's pretty wide but not very deep. He has his hands in a lot of pots that are keeping him afloat. Black voters and moderate voters (which aren't totally exclusive pools) aren't going to be won over by the same policies. I think his unifying theme is electability, obviously, but I do think there are legitimate voters who actually prefer a more centrist candidate. It's going to be interesting to see who is better positioned to pick off some of those.
I think that Biden absolutely has to win at least one of the first three states (Iowa, NH or NV). Hillary won 2 out of 3 of those, and there were still folks pretending that she wasn't the inevitable nominee. Biden can't afford too many hits. SC can only do so much.