The conflict between Real Madrid and Barcelona has long surpassed the sporting dimension, so that elections to the clubs' presidencies are strongly politicized. Phil Ball, the author of Morbo: The Story of Spanish Football, says about the match; "they hate each other with an intensity that can truly shock the outsider".

As early as the 1930s, Barcelona "had developed a reputation as a symbol of Catalan identity, opposed to the centralising tendencies of Madrid". In 1936, when Francisco Franco started the Coup d'état against the democratic Second Spanish Republic, the president of Barcelona, Josep Sunyol, member of the Republican Left of Catalonia and Deputy to The Cortes, was arrested and executed without trial by Franco's troops (Sunyol was exercising his political activities, visiting Republican troops north of Madrid).

Barcelona was on top of the list of organizations to be purged by the National faction, just after communists, anarchists, and independentists. During the Franco dictatorship, most citizens of Barcelona were in strong opposition to the fascist-like régime. During the dictatorships of Miguel Primo de Rivera and of Francisco Franco, all regional languages and identities in Spain were frowned upon and restrained. In this period, Barcelona gained their motto Més que un club (English: More than a club) because of its alleged connection to Catalan nationalist as well as to progressive beliefs. During Franco's regime, however, Barcelona was granted profit due to its good relationship with the dictator at management level, even giving two awards to him. The links between senior Real Madrid representatives and the Francoist regime were undeniable; for most of the Catalans, Real Madrid was regarded as "the establishment club", despite the fact that presidents of both clubs like Josep Sunyol and Rafael Sánchez Guerra, suffered at the hands of Franco's supporters in the Spanish Civil War.

The image for both clubs was further affected by the creation of Ultras groups, some of which became hooligans. In 1980, Ultras Sur was founded as a far-right-leaning Real Madrid ultras group, followed in 1981 by the foundation of the initially left-leaning and later on far-right, Barcelona ultras group Boixos Nois. Both groups became known for their violent acts, and one of the most conflictive factions of Barcelona supporters, the Casuals, became a full-fledged criminal organisation.

For many people, Barcelona is still considered as "the rebellious club", or the alternative pole to "Real Madrid's conservatism". According to polls released by CIS (Centro de Investigaciones Sociológicas), Real Madrid is the favorite team of most of the Spanish residents, while Barcelona stands in the second position. In Catalonia, forces of all the political spectrum are overwhelmingly in favour of Barcelona. Nevertheless, the support of the blaugrana club goes far beyond from that region, earning its best results among young people, sustainers of a federal structure of Spain and citizens with left-wing ideology, in contrast with Real Madrid fans which politically tend to adopt right-wing views.