LONG before that. I have evidence that overt Marxists were involved at high levels of government as early as 1886, and yes, they were Republicans. Marxism always was a creation of the fantastically rich.
The best background books of which I am aware on this is Rabbi Marvin Antelman's To Eliminate the Opiate. Both Volume 1 and Volume 2 are available at Amazon. Although a demanding read, I commend them highly.
Yes. Amity shlaes wrote abut this in The Forgotten Man. The “progressives”, God I hate that word, were pretty disheartened in the 20’s when the economy was booming. They saw their chances to remake the country dashed. But then the great depression happened and they were re-invigorated, the beasts. Many of the progressive leaders who had gone on junkets to Russia to study how they were doing things came back to positions in the Roosevelt administration. They saw all the strife and ruined lives as a VIRTUE, just as they do the strife and ruined lives today. Again I say, the beasts.
Yes, communism was rampant at the Ivy league institutions prior to the Russian revolution, but they were not a fifth column, working for the Russians against the US.
I think that the early draw in Marxism for the pseudo-intellectual elite was the anti-Christian, humanism of communism, the fact that Marxism offered a man-made, political solution to the chaos of the natural world. If the Marxist could regulate the world, they thought that they could prove man’s superiority and that there is no GOD.