Period during the mid 1930s when the communist party sought to ally itself with socialists and new dealers in movements for social change, urging reform of the capitalist system rather than revolution

 It is called popular front

The popular front was a broad coalition of different political groupings, mainly comprising of the communist left, the centrists and the socialists.The Popular Front was critical in  defining true Americanism. It stood for the viewpoint that the country's strength lay in diversity, tolerance, and the rejection of all forms of prejudice.