<P> Reunification with the Social Democratic Federation was long a goal of Norman Thomas and his associates remaining in the Socialist Party . As early as 1938 , Thomas had acknowledged that a number of issues had been involved in the split which led to the formation of the rival Social Democratic Federation , including `` organizational policy , the effort to make the party inclusive of all socialist elements not bound by communist discipline ; a feeling of dissatisfaction with social democratic tactics which had failed in Germany '' as well as `` the socialist estimate of Russia ; and the possibility of cooperation with communists on certain specific matters '' . Still , he held that `` those of us who believe that an inclusive socialist party is desirable , and ought to be possible , hope that the growing friendliness of socialist groups will bring about not only joint action but ultimately a satisfactory reunion on the basis of sufficient agreement for harmonious support of a socialist program '' . Following directions from the Soviet Union , the Communist Party USA ( CPUSA ) and its members were active in the Civil Rights Movement for African Americans . Following Stalin 's `` theory of nationalism '' , the CPUSA once favored the creation of a separate `` nation '' for negroes , to be located in the American Southeast . In 1941 , after Germany invaded the Soviet Union , Joseph Stalin ordered the CPUSA to abandon civil rights work and focus supporting U.S. entry into World War II . Disillusioned , Bayard Rustin began working with members of the Socialist Party of Norman Thomas , particularly , A. Philip Randolph , the head of the Brotherhood of Sleeping Car Porters . The Socialist Party and the SDF merged to form the Socialist Party - Social Democratic Federation ( SP - SDF ) in 1957 . A small group of holdouts refused to reunify , establishing a new organization called the Democratic Socialist Federation . When the Soviet Union led an invasion of Hungary in 1956 , half of the members of Communist Parties around the world quit ; in the U.S. , half did , and many joined the Socialist Party . Frank Zeidler was an American Socialist politician and Mayor of Milwaukee , Wisconsin , serving three terms from April 20 , 1948 to April 18 , 1960 . He was the most recent Socialist mayor of any major American city . Zeidler was Milwaukee 's third Socialist mayor ( after Emil Seidel ( 1910 - 12 ) and Daniel Hoan ( 1916 - 40 ) ) , making Milwaukee the largest American city to elect three Socialists to its highest office . </P>
which goal of the populist party led to the early popularity
Reunification with the Social Democratic Federation