The Socialist Party of Indonesia () was a political party in Indonesia from 1948 until 1960, when it was banned by President Sukarno. Origins In December 1945 Amir Sjarifoeddin's Socialist Party of Indonesia (Parsi) and Sutan Sjahrir's Socialist People's Party (Parsas), both of which had only recently been established, merged to form the Socialist Party. Sjahrir became leader of the combined party. It was popular among young intellectuals and students as well as members of the underground movements led by the two men during the Japanese occupation of Indonesia. At the end of 1945 the Socialist Party gained five of the 25 seats on the working committee of the Central Indonesian National Committee, the de facto legislature. Both Sutan and Amir served terms as prime minister, while other Socialist Party members held senior cabinet posts. From 1947, divisions appeared between Sutan and Amir as Amir and his communist allies gained more and more influence over the party. In June 1947 Amir ousted Sutan. The second party called the Socialist Party of Indonesia was founded on 12 February 1948 by Sutan Sjahrir after his departure from the Socialist Party. Joining him in the new party were Lintong Mulia Sitorus and other followers who agreed with his position on nationalism and not having a strongly pro-Soviet line. The party also launched a newspaper called Sikap which Sitorus edited. The PSI in the Liberal Democracy Era Following the dissolution of the United States of Indonesia and the reestablishment of the unitary Republic of Indonesia in 1950, the PSI was awarded 17 of the 232 seats in the new legislature, the People's Representative Council (DPR), a total in proportion to the estimated strength of the party The PSI held its first party congress in 1952. In the 1955 legislative election the PSI won only 2% of the vote, resulting in five seats in the legislature. This was a far smaller share of the vote than had been expected. The second party congress was held in June 1955. Decline and fall After the 1955 elections, a clear political division between Java and the outer islands opened up. This was followed by a military crisis brought about by army chief-of-staff General Nasution's plan to implement widespread transfers of officers, many of whom had built up private business interests in the regions. On 20 July 1956, the most prominent non-Javanese politician, Vice-president Hatta, resigned with effect from