If it were, Warren's faltering voters would all go to Sanders, not Klobuchar, and Biden's certainly wouldn't go to Sanders. It's class versus identity, and the good angel over my shoulder hopes class wins out. Policy wise Biden is a long way from Sanders, not a 180 degree difference but close to it, but Biden grew up working class and it shows, gaffs and all. People feel that in a gut reaction kind of way.