The USSR has limited leadership available for diplomacy, so to focus that much effort on the USA when the outcome is so farfetched, seems a waste. I personally don't think it will work given the US historical commitment to democracy. They may be in serious trouble economically in 1936, but the moment for dramatic political change was back in 1932. Historically, the communists were very active in the US, but they were shut down as were the German Bunds.
A much better strategy for the USSR diplomats that is within their capability is to get Romania and Turkey into your sphere of influence. Avoid annexing Romanian territory. Elevate the German threat and reduce yours by minimum manning on their borders. Establish strong ties with both through trade. While it is likely that neither will go commie, they can be moved toward socialism by using support your party. If you get Romania or at least prevent them from going over to the Germans, you will have done much to strengthen your southern front. Likewise, Turkey gives you access to the Mediterranean through the Bosporus.