2004 Spanish general election

A general election was held in Spain on Sunday, 14 March 2004, to elect the members of the 8th Cortes Generales. All 350 seats in the Congress of Deputies were up for election, as well as 208 of 259 seats in the Senate. Incumbent prime minister José María Aznar of the People's Party (PP) did not run for re-election, being replaced as party candidate by former deputy prime minister Mariano Rajoy.

Since 2000, the PP had governed with an absolute majority in the Congress of Deputies which allowed it to renegue from its previous agreements with peripheral nationalist parties. This period saw sustained economic growth, but the controversial management—and, at times, attempted cover-up—of a number of crises affected Aznar's government standing and fostered perceptions of arrogance: this included the "Gescartera case", the Prestige oil spill and the Yak-42 crash. A reform of unemployment benefits led to a general strike in 2002, and the unpopular decision to intervene in the Iraq War sparked massive protests across Spain. The electoral outcome was heavily influenced by the Madrid train bombings on 11 March—three days before the election—which saw Aznar's government blaming the Basque separatist ETA for the attacks, in spite of mounting evidence suggesting Islamist authorship. The ruling PP was accused by the opposition of staging a disinformation campaign to prevent the blame on the bombings being linked to Spain's involvement in Iraq.

At 11 million votes and 42.6%, the opposition Spanish Socialist Workers' Party (PSOE) under new leader José Luis Rodríguez Zapatero increased its 2000 result by 3.1 million, securing a net gain of 39 seats to 164. In contrast, the PP, which opinion polls had predicted would secure a diminished but still commanding victory, lost 35 seats and 6.8 percentage points, resulting in the worst defeat for a sitting government in Spain up to that point since 1982. Republican Left of Catalonia (ERC) benefitted from the impact of the "Carod case"—the revelation that party leader Josep-Lluís Carod-Rovira had held a meeting with ETA shortly after joining the new Catalan regional government of Pasqual Maragall—which gave the party publicity to the detriment of Convergence and Union (CiU). The 75.7% voter turnout was among the highest since the Spanish transition to democracy, with no subsequent general election having exceeded such figure. The number of votes cast, at 26.1 million votes, remained the highest figure in gross terms for any Spanish election until April 2019.

The election result was described by some media as an "unprecedented electoral upset". Perceived PP abuses and public rejection at Spain's involvement in Iraq were said to help fuel a wave of discontent against the incumbent ruling party, with Aznar's mismanagement of the 11M bombings serving as the final catalyst for change to happen. Zapatero announced his will to form a minority PSOE government, seeking the parliamentary support of other parties once elected.