Question: How many states make up this nation where its oldest extant political party forms the main opposition party to the federal government ?

text: Socialist International
Members -- Full members
The following parties are full members : [ 28 ] [ 29 ]
The Socialist International (SI) is a worldwide organisation of political parties which seek to establish democratic socialism. It consists mostly of democratic socialist, social-democratic and labour political parties and other organisations. Although formed in 1951 as a successor to the Labour and Socialist International, it has antecedents to the late 19th century. The organisation currently includes 147 member parties and organisations from over 100 countries. Its members have governed in many countries including most of Europe. The current secretary general of the SI is Luis Ayala [Wikidata] (Chile) and the current president of the SI is the former Prime Minister of Greece, George Papandreou, both of whom were re-elected at the last SI Congress held in Cartagena, Colombia in March 2017.
Country Name Abbr Government Notes
Albania Socialist Party of Albania PS in government Admitted as consultative member in 1999 . Promoted to full member in 2003
Algeria Socialist Forces Front FFS in opposition Admitted as consultative member in 1992 . Promoted to full member in 1996
Andorra Social Democratic Party PS in opposition Promoted to full member in 2003
Angola Popular Movement for the Liberation of Angola MPLA in government Admitted as observer member in 1996 . Promoted to full member in 2003
Argentina Radical Civic Union UCR junior party in coalition Admitted as consultative member in 1996 . Promoted to full member in 1999
Armenia Armenian Revolutionary Federation ARF in opposition Admitted ( as Armenian Socialist Party ) as observer member in 1996 . Promoted ( as ASP ) to consultative member in 1999 . Promoted ( as ASP ) to full member in 2003
Austria Social Democratic Party of Austria SPÖ in opposition Full member since 1951
Azerbaijan Social Democratic Party ASDP in opposition Admitted as observer member in 1996 . Promoted to consultative member in 2003 . Readmitted as consultative member in June/July 2014 . Admitted as full member in 2016
Belarus Belarusian Social Democratic Party BSDP in opposition Admitted as observer member in 1999 . Promoted to consultative member in 2003 . Promoted to full member in November 2015
Belgium Socialist Party PS in opposition
Bosnia and Herzegovina Social Democratic Party of Bosnia and Herzegovina SDP BiH in opposition Admitted as observer member in 1996 . Promoted to full member in 1999
Brazil Democratic Labour Party PDT in opposition Admitted as consultative member in 1986 . Promoted to full member in 1989
Bulgaria Party of Bulgarian Social Democrats PBSD in opposition
Bulgaria Bulgarian Socialist Party BSP in opposition Admitted as full member in 2003
Burkina Faso People 's Movement for Progress MPP in government Admitted as full member in 2016
Cameroon Social Democratic Front SDF in opposition Admitted as consultative member in 1996 . Promoted to full member in 1999
Cape Verde African Party for the Independence of Cape Verde PAICV in opposition Admitted as consultative member in 1992 . Promoted to full member in 1996
Central African Republic Movement for the Liberation of the Central African People MLPC in opposition Admitted as observer member in 2008 . Upgraded to full member in 2018
Chad National Union for Democracy and Renewal UNDR in opposition Admitted as observer member in June/July 2014 . Upgraded to full member in 2017
Chile Party for Democracy PPD in opposition Admitted as consultative member in 1992 . Promoted to full member in 1996