The initial federal constitution of 1949 was replaced in 1950 by a unitary but still provisional constitution. It was parliamentary in character and assigned an essentially figurehead role to the president. From the revolutionary period, Indonesia had inherited a multiparty system. The main parties after independence were the major Muslim party, Masyumi (Masjumi); the Muslim theologians' party, Nahdatul Ulama (NU), which seceded from Masyumi in 1952; the Nationalist Party (PNI); the Communist Party (PKI); the "national communist" party, Murba; the lesser Muslim parties, Perti and Partai Sarekat Islam Indonesia (PSII); and the Socialist Party (PSI). Until the first elections were held, in 1955, Parliament was filled by appointment under a gentlemen's agreement between parties as to their probable electoral strengths. The elections of 1955, a remarkable and technically successful experiment in the exercise of political choice by a largely nonliterate population, confirmed the position of Masyumi, NU, PNI, and PKI as the country's four leading political parties.

Indonesian Parliament - 1955

With the exception of the PKI, the parties did not represent clearly opposing interests or programs, though some broad bases of support could be seen. The PNI was particularly strong in the ranks of the civil service, while Masyumi tended to find its support in market towns and among the trading classes; NU was stronger in rural areas. The PSI, an influential party until it was virtually eliminated in the elections, had strong support in the higher ranks of the army and bureaucracy. Also important was the regional distribution of party strengths. The PNI, NU, and PKI were essentially Java-based parties, while Masyumi drew most of its strength from outside Java, particularly in western Sumatra and southwestern Celebes (Sulawesi). Its support within Java was to be found mainly in Jawa Barat (West Java) province, the home of the Sundanese and not of the ethnic Javanese. This unevenness in party strengths meant that political rivalry in the early years of independence tended to have a regional flavour, a fact that was of importance when regional resistance to the centre reached the point of open revolt in 1958. In simplified terms, it is possible to see, in the regional distribution of party strengths, a broad opposition between the hierarchical, rice-based society of Java and the more strongly Muslim areas where commerce rather than agriculture has been dominant. Any interpretation of political conflicts in Indonesia also must take account of the extent to which the parties and their suborganizations reflected major cultural streams (aliran) in Indonesian society rather than interests, classes, or even regions. In addition to Masyumi's suspicion of the Javanese parties, the division within Java between santri (devout Muslims) and abangan (reflecting an earlier, pre-Muslim syncretism) is important in understanding the rivalry of the NU and Masyumi, on the one hand, and the PNI and the PKI, on the other.

In the early and mid-1950s there was a rapid succession of governments--Hatta (December 1949-August 1950), Mohammad Natsir (September 1950-March 1951), Sukiman Wirjosandjojo (April 1951-February 1952), Wilopo (April 1952-June 1953), Ali Sastroamidjojo (July 1953-July 1955), Burhanuddin Harahap (August 1955-March 1956), and Ali's second government (March 1956-March 1957).

This instability created a growing disillusionment with the fruits of independence and a sense of contrast between the heroism of the revolution and the self-seeking party rivalry that followed it. In particular, conflict between the export-producing outer islands and the heavily populated island of Java was becoming more marked. In December 1956 these factors of discontent led to movements of regional dissidence, supported by local military commanders, in western Sumatra, the Minahasa Peninsula of northern Celebes, and elsewhere.