Spain is a constitutional monarchy ruled by King Juan Carlos I and governed by a democratically elected General Court comprising of two chambers; the Congress of Deputies and the Senate (the upper house). Once elected these chambers serve for a four year term. Election is by proportional representation. The most recent election, in 2004, saw José Luis Rodríguez Zapatero and his socialist PSOE (Partido Socialista Obrero Español) beat José Maria Aznar’s centre-right PP (Partido Popular), winning 43.3 % of the overall vote.