Two months away from Singapore's separation with Malaysia, UPP chief and only Assembly Member Ong Eng Guan resigned his seat and retired from politics, citing the infrequent legislature sessions as the reason. This very last election for the Legislative Assembly was a straight fight between the two main parties, PAP and Barisan, and their candidates were former PAP Assembly colleagues. The bombing of MacDonald House by two Indonesian soldiers three months earlier on 10 March 1965, as part of President Sukarno's "Konfrontasi" against Malaysia, gained PAP some support from voters who decided to back the ruling party (the soldiers were consequently handed the death penalty). By then, PAP was a nationwide party with a presence in the Peninsular. Apart from having 12 appointed representatives in Malaysia's Parliament, PAP contested 11 seats in the 1964 Malaysia General Election and won one. However, the move soured its relations with the ruling Alliance Party of Malaysia. Matters worsened after PAP and several opposition parties established the Malaysian Solidarity Convention on 9 May 1965 to campaign for a "Malaysian Malaysia", which was perceived to be challenging the special position of ethnic Malays. The PAP state government also proposed to the Alliance federal government for a looser confederation consisting of Singapore, Sabah, Sarawak and Penang, if the different views on autonomy were difficult to bridge. These factors became catalysts for the expulsion of Singapore. Newly-elected Assembly Member Lee Khoon Choy was sworn in only four months after the by-election, directly as a Member of Parliament at the opening of the Republic of Singapore's first Parliament. With the gaining of independence, Singapore's 15 seats in Malaysia ceased. Members of PAP Malaysia, including its lone elected representative C. V. Devan Nair, founded Democratic Action Party when their party was de-registered by the Malaysian authorities. In 1969, Nair quit Malaysian politics and returned to Singapore.

Writ of election: 23 June 1965 [Wed]
Nomination day: 30 June 1965 [Wed]
Polling day: 10 July 1965 [Sat]
Member swearing-in (at 1st Parliament): 8 December 1965 [Wed]

Eligible voters: 11,837
Voter turnout: 10,858 (91.7%)

Election deposit: $500

Hong Lim

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By-Elections 1967
General Election 1968