|Merger of||Internationalist Communist League|
Workers Revolutionary Party
|Succeeded by||Left Bloc|
|Political position||Left-wing to far-left|
|International affiliation||Fourth International|
The Revolutionary Socialist Party (Portuguese: Partido Socialista Revolucionário, pronounced [p'tidu susi?'li?t? vulusiu'na?iu], or PSR) was a small left-wing to far-left party in Portugal, founded in 1978 after the merger of two Trotskyist parties - the Internationalist Communist League (Portuguese: Liga Comunista Internacionalista or LCI) and the Workers Revolutionary Party (Portuguese: Partido Revolucionário dos Trabalhadores or PRT). The LCI and PRT were both part of the reunified Fourth International. The International recognised the PSR as its Portuguese section.
In 1998 Party renamed itself in order to join with some other left-wing parties in founding the Left Bloc (Portuguese: Bloco de Esquerda or BE). The organisation retains the acronym PSR, and has become the association "Revolutionary Socialist Politics". The historical leader of the PSR is Francisco Louçã, who would become leader of the Left Bloc.
The party had never achieved parliamentary representation before the merger in the Left Bloc, although it may be considered the 3rd or 4th biggest left-wing Party in the country.
In 1983, the Party ran in the legislative election in coalition with the People's Democratic Union (Portuguese: União Democrática Popular or UDP) in some constituencies, receiving 0.4% in those constituencies and 0.2% in the others In 1985, after some splits, the Party gained a new life, mainly due to its anti-militaristic and anti-racist campaigns and in that year's election, the PSR got 0.6% of the vote. In 1987, the Party contested the first European Election held in Portugal, achieving 0.5%, and in the legislative election, achieving 0.6%.
Also in 1987, the Party started publishing of the Combate (Struggle) monthly newspaper. In elections for the European Parliament of 1989, the PSR got 0.8%.
In the legislative election of 1991 got 1.12%, the best result in the Party's history. It ran for the last time in an election in 1995, achieving 0.6%.
In 1998, the party formed a permanent coalition with the People's Democratic Union, the Politics XXI and the Left Revolutionary Front, creating the Bloco de Esquerda (Left Bloc). In 2005, in the last congress in the party's history, it changed its status from a party to a political association, which became extinct in 2013.