[1] The group was founded in December 1974 by Manuel Serra,[2] a Marxist who had previously attempted to become leader of the Socialist Party.

[3] Under his leadership, the FSP took place in violent demonstrations, including riots in Setúbal.

[4] In the 1975 Constituent Assembly election, the FSP received less than 5% of the vote and won zero seats.

[5] The FSP ran candidates in the 1976 legislative election,[1] and participated in the 1976 local election in coalition with the Portuguese Communist Party and the Portuguese Democratic Movement inside the Electoral Front United People.

[citation needed] On 7 July 2004, after several years of inactivity, the party was declared extinct by the Portuguese Constitutional Court.