the reason we refer to the far left as Marxist is because that's what they are. it's not name calling. it's a fact. that's why, when you read through the literature from communist party USA or socialist party USA, they openly say that they work through the "progressive" wing of the democrat party. it's not a secret.
everything from the so called green movement, to the unions, to the call for income equity is straight out of Marx/Engles. the father left you go, the more they embrace all that Marx wrote about.
problem with most on the left is that they don't bother to learn this stuff so they think they are embracing something new and wonderful. if you are supporting liberal candidates, this is what you are supporting.