If that is true, then it sounds like the Dems should start catering to the left, instead of telling them to sit down and shut up.
Additionally, that poll says "...a top reason...", not the only reason. Look at the other issues listed in the poll:
- The economy
- Medicare and Social Security
- Immigration and border security
- Healthcare
- Abortion policy
All things that the Democrats keep campaigning on, but doing practially nothing about.