In late USSR miners were one of the most active strata. Pretty left. One can say, the only clearly left of that time’s protesters, because, well, around 1988 the general public in USSR was fed up with left ideologies.

See this https://en.wikipedia.org/wiki/The_Iron_Heel_of_Oligarchy (it’s not too shit, from the eyes of Communists trying to find themselves a place in the society that is over them). EDIT: It’s an illustration to “fed up”, not to late USSR.