The work of Diego Rivera and Frida Kahlo were full to the brim with left-leaning political statements, sometimes subtle, sometimes very direct. They made no secret of their dislike for modern day capitalism which even led to one of Rivera's largest projects being rejected by it's donor (Man at the Crossroads) due to the inclusion of a portrait of Lenin, among other things.
Artist Rivera held an exhibition at MoMA as far back as 1931 and he decided to produce eight frescoes for this, designing them in a way that they could easily be transported to and from the venue. He was well taken care of by this institution who were very keen to bring his work into their display and even provided a studio for him to work from in order to complete this request. In return he worked tirelessly for over a month in order to finish the series in time. He was also given a greater freedom of expression than some of his donors had given him within the US at other times.
Art history is littered with artists who have failed to gain acceptance within their own career but Diego Rivera was not such an artist. The exhibition was to break attendance records at this prestigious institution and this then led on to further commissioned artworks within the US. The combination of political messages and native Mexican colour and vibrancy seemed to strike a cord with some elements of American society, even if their own political beliefs did not match.