I would suppose it was published somewhere. Otherwise, where it come from?
Not all speeches made are published. They come from those that attended, their notes, and transcripts.
I really doubt that the Political Bureau of the Central Committee of the Communist Party of the Soviet Union has opened their archives; but maybe it is available on the CPUSA archives.
http://dlib.nyu.edu/eadapp/transform?source=tamwag/rcp.xml&style=tamwag/tamwag.xsl&part=body
Guide to the Revolutionary Communist Party, USA. Collection
Well, it’s not a Founding Father, so it’s likely not one of the many David Barton fabrications! :-)