There is no left wing that is uniquely American. Internationalist Marxists are the same worldwide. Even a cursory study of their philosophy reveals a contempt for all cultures; in the last chapter of the Manifesto, they express their intent to engage in “the forcible overthrow of all existing social conditions”, across the globe.
Which is failing because look at the growth of political parties that are right-leaning or are bordering on the right, this is a global change going on.