PUP was founded in December 1974 by the Mendes fraction of the Communist Party of Portugal (Marxist-Leninist).

[citation needed] The PUP published a newspaper called Averdade (The Truth).

It rejected parliamentary democracy and sought to create a people's republic of poor workers and peasants.

[1] After the 1975 elections PUP was renamed Portuguese Marxist-Leninist Committee (Comité Marxista-Leninista Português).

[citation needed] In 1976 CMLP merged with the Portuguese Marxist-Leninist Communist Organization and the Organization for the Reconstruction of the Communist Party (Marxist-Leninist) to form the Portuguese Communist Party (Reconstructed).