The one overlap between Sanders and Warren is their relative appeal to young people. This stands in contrast to Biden, for whom the greatest predictor of support is age. The older you are, the more likely you are to be ridin' with Biden. This suggests that the progressive tussle between Warren and Sanders is about more than a competition for Rep. Alexandra Ocasio-Cortez's (D-N. Y.) endorsement; it's really about the future of the party... Already, progressives are setting the pace for new and popular policy ideas. Reformer, or revolutionary? The policies may be similar, but the results could be dramatically different.