I seem to recall it coming in from the Reagan era onwards. I also recall reading in the society/fashion news (oh, reading the "women's sports pages," as my S.O. teases me,) Nancy Reagan, coming in as a very high society oriented first lady after the very abstemious Carter White House (i.e., no alchohol, Roslyn liked sewed her own clothes, inexpensive fetes,) made a big impact dressing in red a lot. I also recall, then "they" started calling it "wearing Republican red," because it was cool or something to be a Republican. (Remember, in those days, someone like Ariana Huffington was trying to claw her way into some power in Republican social circles.)

I always thought that may have influenced the press in chosing red for the Republican states, it really was a big deal in trends, the "Republican red" thing.

Certainly Nancy didn't think of red as communist at all, or Ronnie the commie fighter wouldn't have gone gaga over her. (heh, I also recall she didn't get along too well with Raisa Gorbachev.)

Nancy's red was really a bold thing, sort of iconographic. In the olden daze, red was not a respectable color for a lady to wear--there's a famous scene regarding that in Gone with The Wind. Prior to the 80's, old school Republican WASP's would still wear pastels, not bright colors like that.