[1] In January 1946, the party and its youth wing Pesindo, along with all other major political forces at the time, joined the Tan Malaka-led national front (Persatuan Perdjuangan).
Sukarno offered the Persatuan Perdjuangan to form a new cabinet, but such a government never materialized due to conflicts inside the front.
This ultimatum created a split inside the Socialist Party, as Sjahrir expressed some conciliatory attitudes towards the Dutch positions.
When Sjahrir had travelled to address the United Nations, Sjarifuddin was appointed acting party chairman.
When Hatta formed a new government, the Sjajrir-led faction of the Socialist Party supported it whilst the rest of Sajap Kiri opposed it.