Masakazu Sekiguchi Hiroyuki Nagahama Yukihiko Imasaki Kazuo Ueda
The party was established in December 1948 by members of the Socialist Party Orthodox Faction Diet Members' Group, which was formed by 16 National Diet members who had resigned or been expelled from the Japan Socialist Party after voting against the budget proposed by the Democratic Party–Socialist government due to their opposition to an increase in public transport fares.
[1] It was particularly well-supported in Okayama and Hokkaido where party president Hisao Kuroda and Haruo Okada were based, and was supported by some members of the National Railwaymen's Union and National Communications Workers' Union.
[1] It won only seven seats in the January 1949 elections, and was further reduced in size by three defections over the party's unclear stance on the Korean War.
[1] It won two seats in the 1950 House of Councillors elections, and retained its four remaining seats in the House of Representatives in the 1952 general elections.