I dug into your book last night, and suddenly had a useful memory. Back at the end of his career (in the 1970s), Eric Sevareid would do these editorials at the end of the CBS evening news. In one of these, which — me being a “Teenage Republican” in a very liberal town at the time — blew me away, Sevareid said that if fascism ever comes to the United States, it will come disguised as liberalism. I forget the context, but I remember the editorial having rocked my world and running around quoting it thereafter for some time.
I have no idea whether it is possible to dig up the old Sevareid editorials, but if I had to guess the comment emerged at the very end, 1976 or 1977. I did not become interested in politics until then, and I do remember that he was old as the hills.
Anyway, interesting stuff.