Organization: CNN/Edison Research Center
Conducted: March 2020
Exact wording: A government plan for all instead of private insurance.
Sample Size: 607 Democratic primary voters,
Overall Findings: 65% support, 30% oppose
Party Lines: n/a
Summary: Exit polling from the 2020 Washington Democratic primary found that 65% of voters support Medicare for All. Despite the policy having strong Democratic support, Democratic primary voters still turned out better for Joe Biden than Bernie Sanders, even though Biden did not run on Medicare for All but Sanders did. This trend was visible across several states during the 2020 Democratic Primary.
Link to the poll: https://www.cnn.com/election/2020/primaries-caucuses/entrance-and-exit-polls/mississippi/democratic