If you visit Real Clear Politics, you will note post last week’s debates, former Vice President Joe Biden has twice the support as does Senator Bernie Sanders and even more so than does Senator Elizabeth Warren.
However, add Sander’s and Warren’s poll numbers together and their popularity is equal to that of Biden.
Normally that would not mean much. But given that Biden represents the center of the Democrat Party and Sanders / Warren represent the left wing, it may be significant.
Democrats can’t afford supporters not showing up in the polls in 2020 as they failed to do in 2016.