The Democratic Socialist Federation was a small group of dissenting members of the Social Democratic Federation who opposed the latter's reunification with the Socialist Party of America in 1956. The Social Democratic Federation was a Political party in the United States. The Socialist Party of America (SPA was a socialist Political party in the United States. Year 1956 ( MCMLVI) was a Leap year starting on Sunday (link will display full calendar of the Gregorian calendar. They remained essentially a paper organization until they too reunified with the party in 1972, at the invitation of the followers of Max Shachtman to provide the votes necessary to consolidate their power over the organization and refashion it into the Social Democrats USA. Year 1972 ( MCMLXXII) was a Leap year starting on Saturday (link will display full calendar of the Gregorian calendar. Max Shachtman ( September 10 1904 - November 4, 1972) was an American Marxist theorist For the earlier political party see the Social Democratic Party (USA.