From the early 90's onwards attacking PC (after several decades of post-New Left ironic,mocking, tongue in cheek refs. to PC and PI), was a Rightist trope, what with cover stories in the newsweeklies, comments by Bush 41, etc.
But, as more than I know here, PC as a term was in wide use on the Leninist left from the 30's onwards. Having just returned that bound volume of the New Masses from 1947 to the library, I was reminded of this.
If I get from interlibrary loan, an extensively documented book by ex-CPUSA (1947-1958) neo-con historian Aileen Kraditor, "Jimmy Higgins: Inside the Mental World of American Communists, 1930-1958, " with zillions of quotes from The Daily Worker, The Communist, Organizer, New Masses and other CPUSA journals, " where acceptable lines are called, "politically correct, " and bad ones, "politically incorrect, " I could cite many examples of the past history on the Old Left of this usage.
I'll try not to overpost today, btw. Not only Chris Doss ;-) is a hothead here...as JD knows too and snitsnat ;-) from offlist nastiness by Jim and I towards each other yesterday and in the last few weeks shows.
"Excitable Boy, " Zevon Pugliese.