Who? Biden? I don't think so. Then you have some good potential candidates in the lower tier, but their numbers are in the single digit. No one has risen above in that second tier.
Now, in RealClearPolitics, the polls show that in Iowa, Bernie is the only one that shows a positive win vs Trump. https://www.realclearpolitics.com/ep...ders-6788.html
So, I also would not underestimate the power of the more progressive arm of the Democratic Party to fare better than the "middlin'" Democrats. People want change. That's how Trump got elected.