As a historical exercise, I listened to Huey Long. He should be considered a Communist measured by any yardstick. His popularity was snowballing and he could have been elected President. If you're spooked by seeing how far left some Democrats are, consider that Huey Long's brand of politics faded out. The Democratic Socialists could follow the same path.
Back then the movement was known as "Share The Wealth" clubs. There were thousands of such clubs.