[1] The merger occurred in order to consolidate their relatively compatible and similar aims, that of gradual and nonradical progressivism implementing liberal policies.

[1] The merger occurred because of the weak performance of both parties in the Singapore general election of 1955, but members started to merge with the Singapore People's Alliance (SPA) before the following general election of 1959.

Following the election most of the LSP merged with the SPA and the rump of the LSP died out as the now ruling People's Action Party (PAP) gained dominance.

The SPA faded away during the incidents of merger, ensuing heated PAP-UMNO relations, and a shifted political focus towards an additional struggle between the PAP and the Barisan Sosialis.

The LSP ceased to exist by 1965, when Singapore became fully independent, and never stood candidates for election.