Socialist Party (PS). The Socialists were founded in 1973, sensing the oncoming return of democracy, with significant aid from the German social democrats.
The party won the 1975 election to the constituent assembly and thus had a strong hand in drafting the constitution, it subsequently won the 1976 election as well.
The party has been the dominant party of government since 1995, spending all but three years in government until its 2011 election loss.
The party is a fairly typical mainstream centre-left party and like most moved closer to the centre in the 1990s and early 2000s.
The party has won both absolute majorities (its most recent was in 2005) and minority governments in the past. In the case of a minority it can rely on the far-left parties to make sure it can govern, but sometimes need PSD help in passing economic policy. The party did, on one occasion, form a grand coalition with the PSD between 1985 and 1987, though this experiment has not been repeated since.
The party lacks the strong ties to organised labour and trade unionism of other major European centre-left parties due to its late formation, the historic strength of Portuguese Communism and because of the repressive Estado Novo regime.
The PS is stronger in the South of Portugal, where the Catholic Church is weaker, people are poorer and inequality is far higher with property generally owned by a small number of powerful families. The party is also strong in Portugal’s two biggest cities of Lisbon and Porto.
The PS is a broadly pro-European party.
Despite being in charge during the financial crisis the PS currently polls well. Despite negotiating an EU bailout in the midst of the 2011 election campaign the PS ran a strong campaign arguing that its delayed action was due to its position as a defender of Portuguese sovereignty after the PS government held out for the last possible minute to agree to a bailout. Nonetheless voters are under no apprehension that if the PS were in power it would also be committed to the austerity programme.
The party sits in the Socialists and Democrats group to whom it demonstrates broadly average loyalty at 97.8%.