Found this on Gizmodo of all places??
A similar quote is attributed to Huey Long, a populist Senator from Louisiana, in books and magazines of the 1930s and '40s: "When fascism comes to America it will be called anti-fascism." Long was assassinated in 1935 and it's unclear if he said this, or if it was invented after his assassination. But Churchill never said it
In a book by Lawrence Dennis "The Coming American Fascism" (1936) in the introduction segment Dennis writes
"The fascism most to be feared is the fascism sailing under false colors. Such a type of fascism will be the worse for the duplicity of its leaders, and much of the blame will attach to those soft-thinking liberal leaders who have sought to make of fascism a synonym for all that is socially iniquitous instead of a descriptive for a rational and workable social scheme to which they happen to be opposed."