FiveThirtyEight has their daily primaries national polling aggregate up and running. If you're into such things, it's a pretty great tool. You can go to your state polling (if available) through a simple drop down menu too.

https://projects.fivethirtyeight.com/polls/president-primary-d/national/

Current national poll averages:
Biden
26.2%

Sanders
17.0%

Warren
14.9%

Buttigieg
9.6%