The National Union (Portuguese: União Nacional) was the sole legal party of the Estado Novo regime in Portugal, founded in July 1930 and dominated by António de Oliveira Salazar during most of its existence.

The National Union membership was mostly drawn from local notables: landowners, professionals and businessmen, Catholics, monarchists or conservative republicans.

[18] At no stage did it appear that Salazar wished it to fulfill the central role the fascist party had acquired in Mussolini's Italy; in fact, it was meant to be a platform of conservatism, not a revolutionary vanguard.

[19] The National Union's ideology was corporatism, and it took as many inspirations from Catholic encyclicals such as Rerum novarum and Quadragesimo anno as well as from Mussolini's corporate state.

[21] The National Union was set up to control and restrain public opinion rather than to mobilize it, and ministers, diplomats and civil servants were never compelled to join the party.

Salazar himself criticized the "exaltation of youth, the cult of force through direct action, the principle of the superiority of state political power in social life, [and] the propensity for organizing masses behind a single leader" as fundamental differences between fascism and the Catholic corporatism of the Estado Novo.

Scholars such as Stanley G. Payne, Thomas Gerard Gallagher, Juan José Linz, António Costa Pinto, Roger Griffin, Grzegorz Rossoliński-Liebe and Arnd Bauerkämper,[24] as well as Howard J. Wiarda, consider the Portuguese Estado Novo conservative authoritarian and not fascist.

Salazar denounced the National Syndicalists as "inspired by certain foreign models" (meaning German Nazism) and condemned their "exaltation of youth, the cult of force through direct action, the principle of the superiority of state political power in social life, [and] the propensity for organizing masses behind a single leader" as fundamental differences between fascism and the Catholic corporatism of the Estado Novo.

The first Central Commission was composed by Bissaia Barreto, João Amaral, a judge and an integralist monarchist, and Nuno Mexia, who had been linked to the Union of Economic Interests (União dos Interesses Económicos) in the 1920s.

This lethargy can be partly explained by the affirmation by the regime that it did not attribute great importance to it beyond its utility as an electoral and legitimating vehicle.

It contrasted the supposed stability of the Estado Novo, as opposed to the pre-1926 republican government which "transformed the country‟s public life into something like a tribal African disorder".

The measures included parliamentary elections, a general political amnesty, restoration of freedom of the press, curtailment of legal repression and a commitment to introduce the right of habeas corpus.

The opposition to Salazar started to organize itself around a broad coalition, the Movement of Democratic Unity (MUD), which ranged from ultra-Catholics and fringe elements of the extreme right to the Portuguese Communist Party.

In 1970, two years after Salazar had been replaced as a leader and prime minister by Marcelo Caetano, the name of the party was changed to Acção Nacional Popular ("People's National Action").

[35] Under Caetano, the party and the regime further softened its rule - the police is reported to "have become more respectful of legality [...] and would spare systematically moderate opponents", and the People's National Action proclaimed that it would move "toward a degree of pluralism".

Graham and Makler wrote that this reform proved revolutionary: "Within months the sindicatos, which for decades had been trade unions in name only, began to be transformed from amorphous government agencies into genuine instruments of the workers.