As the Guardian has noted, the De Moines Register (a newspaper in Iowa, USA, with a good track record on polling) has done a poll on the US primaries, which happen first in that state. Joe Biden topped the poll, and is not a candidate. Sanders was second.
More interesting from my perspective was this:
The Green New Deal, a proposal by Democrats in Congress to tackle climate change, was supported in full by 65% of the Democratic voters, partially by 26%, with 4% against. The deal would fund government programs on clean energy and make buildings energy efficient while helping to address poverty.
That's impressive polling. 91% of US Democrats wholly or partially back the Green New Deal. Few ideas ever get that much support in any party.