2015 Spanish general election

A general election was held in Spain on Sunday, 20 December 2015, to elect the members of the 11th Cortes Generales under the Spanish Constitution of 1978. All 350 seats in the Congress of Deputies were up for election, as well as 208 of 266 seats in the Senate. At exactly four years and one month since the previous one, this remains the longest timespan between two general elections since the Spanish transition to democracy, and the only time in the country that a general election has been held on the latest possible date allowed under law.

Immediately after assuming office following the 2011 election, the new government under Prime Minister Mariano Rajoy adopted an austerity agenda including social spending cuts, tax hikes and a harsh labour reform to address the ongoing economic crisis (amid soaring unemployment, public deficit and risk premium), as well as a bailout of the banking system through the European Stability Mechanism, which were met with widespreat protests and two general strikes in 2012. From 2013 onwards, a number of corruption scandals affecting the ruling People's Party (PP)—most notably, the Bárcenas affair, the Púnica case and the ongoing judicial probes into the Gürtel case—further weakened the government's position and increased social distrust in traditional parties. During this period, the Monarchy underwent a reputation crisis over King Juan Carlos I's elephant-hunting trips and the Nóos case involving Infanta Cristina and her spouse, leading to the King's abdication in favour of his son, who acceded to the throne as Felipe VI.

Public discontent with the political system showed up in the results of the 2014 European Parliament election in Spain—which saw the emergence of newcomer parties Podemos (Spanish for "We can") and Citizens (C's), presenting themselves as heralds of "new politics" and curtailing expectations for the more traditional United Left (IU) and Union, Progress and Democracy (UPyD)—while the 2015 local and regional elections resulted in a wipeout of most of the PP's territorial power in favour of left-wing administrations. The resignation of Alfredo Pérez Rubalcaba as leader of the main opposition Spanish Socialist Workers' Party (PSOE) triggered a leadership contest which was won by Pedro Sánchez. In Catalonia, opposition to the ruling PP served as a catalyst for a pro-independence push being supported by regional authorities under Convergence and Union (CiU), which held a non-binding self-determination referendum in 2014 defying orders from the Constitutional Court. The outcome of the 2015 Catalan regional election briefly boosted C's polling numbers before dwindling to a Podemos's electoral comeback during the general election campaign.

The election saw the PP, PSOE and IU scoring historical lows, with Rajoy's party seeing the largest loss of support for a sitting government since 1982. Podemos and C's won a combined 109 seats and over eight million votes, mostly at the cost of the main traditional parties, the IU-led Popular Unity platform, UPyD and peripheral nationalist parties: aside of a major breakthrough by Republican Left of Catalonia (ERC) and the breakup of CiU after 37 years of existence, support for the abertzale left EH Bildu fell sharply, the Basque Nationalist Party (PNV) stagnated, Canarian Coalition (CC) clung on to a single seat and both Geroa Bai and the Galician Nationalist Bloc (BNG) were shut out from parliament. With the most-voted party obtaining just 123 seats and a third party winning an unprecedented 69 seats—the previous record being 23 in 1979—the result marked the transition from an imperfect two-party system to a fully-fledged multi-party system. After months of inconclusive negotiations, neither PP or PSOE were able to garner enough votes to secure a majority, leading to a fresh election in 2016.