Article 68.1SC stipulates that Congress must consist of at least 300 and at most 400 deputies, chosen through universal, free, equal, direct and secret suffrage. This is done through a system of proportional representation. The number of deputies has been set on 350 deputies by the Organic Electoral Law of March 1977. Article 68.2SC designates the provinces as constituencies in which the electoral threshold has been set on three percent. The electoral law has determined that each province may at least delegate two deputies. In addition, both the autonomous enclaves Ceuta and Melilla may each delegate one deputy. As a result only 248 seats remain to be distributed proportionally. Combined with the three percent threshold and the division of residual seats according to the largest average, the proportionalness of the system of representation as determined by article 68.3SC appears rightly questioned by L. Prakke.
The Senate is the house of territorial representation (art. 69SC). As such, it also represents the autonomous communities. Each community delegates one senator and may delegate one more for every million inhabitants (art.69.5SC). Primarily however, the Senate represents the provinces of which al the provinces situated on the mainland each elect four senators. The islands which represent the three remaining provinces; Las Palmas, Santa Cruz de Tenerife and the Balearic Is1ands are all individually represented in the Senate. The bigger islands Mallorca, Gran Canaria and Tenerife each delegate three senators. The smaller islands Menorca and Ibiza and formentera, Lanzarote and Fuerteventura, and la Palma, la Gomera and Hierro, each delegate one senator. Both Moroccan enclaves Ceuta and Melilla furthermore each delegate two senators but their recent conversion into autonomous communities allows them to each delegate at least one extra senator (art. 69.4SC).
According to l. Prakke the territorial representation does not really live up to its promise as the senators are more inclined to follow party politics than territorial insights. After the 1993 elections however, it appeared that most of the representatives of the Catalan autonomous communities came forth from the Regional Catalan party, the UiC. In this case party politics are very likely to coincide with regional insights. In 1994, in a special senatorial debate on the future structure of the senate it was decided change its structure drastically in favour of the autonomous communities. To this end, a special committee has been set up, supported by all parties, which will propose a new structure of the Senate. In this new structure the Senate should represent the autonomous communities in their relation to the central state and their interests in regard to financial transfers and their relations with the European Union .