Article 12 of the Spanish Constitution of 1931 allowed for Spanish provinces to be organized into "autonomous regions", provided that a regional Statute was proposed by a majority of the provinces' municipalities comprising at least two-thirds of the provincial population and that two-thirds majority of all those eligible to vote accepted the draft Statute.

[2] The 1931 Spanish constitution was not clear on whether the two-thirds approval requirement was applicable to each province or to the total vote figures.

In December 1933 the Basque Nationalist Party recommended to proceed on basis of the total vote figure being over the two-thirds threshold.

The draft Statute was subsequently submitted to the consideration of the Cortes, which initially rejected it on 28 January 1934 by a 125–136 margin as a consequence of popular support not reaching the required two-thirds majority in Álava.

However, after the Popular Front's victory in the 1936 general elections, the statute was approved on 1 October 1936, though its application would be severely limited as a result of the outbreak of the Spanish Civil War.