|Leader||Diego Martínez Barrio|
|Merger of||Radical Democratic Party|
Radical Socialist Republican Party
|Merged into||Spanish Democratic Republican Action|
|National affiliation||Popular Front|
It was formed as a result of a merger of several small republican parties, most notably Diego Martinez Barrio's Radical Democratic Party and the Radical Socialist Republican Party, both of which had split away from the more moderate Radical Republican Party of Alejandro Lerroux.
Integrated in the Popular Front ahead of the 1936 election, the party won 38 seats becoming the fourth largest party. It formed a governing coalition with Manuel Azaña's Republican Left. Though it participated in all republican governments during the Spanish Civil War, it played a minor role starting under Largo Caballero's government.
- Nigel Townson. The Crisis of Democracy in Spain: Centrist Politics Under the Second Republic, 1931-1936. Sussex Academic Press. 2000. pp. 2–3.
- Beevor, Antony. The Battle for Spain. The Spanish Civil War 1936-1939. Penguin Books. 2006. p. 456.