With no outright winner in last December's poll and no breakthrough in talks since then on a workable coalition, the country is forced into a new election. The impasse and the new vote amount to uncharted territory for Spain, which returned to democracy three years after the death of dictator Francisco Franco in 1975. Failure to form a government after the June poll will compound the uncertainty.
The country has enjoyed the relative stability of a system dominated by just two parties: the centre-right People's Party (PP) led by Acting Prime Minister Mariano Rajoy and the Socialist Workers' party (PSOE), led by Pedro Sánchez.
Britain's Guardian newspaper described Spain since 1978 as a two-party state with mostly minority PP or PSOE governments, propped up by Basques and Catalans in return for more autonomy. Newcomers, business-friendly Ciudadanos and anti-austerity Podemos, have broken the two-party stranglehold. But coalition-building has become more difficult, with parties accusing their potential partners of unrealistic demands and intransigence.
Rajoy became leader of the People's Party in 2004 and Prime Minister of Spain in 2011 following his party's landslide that year in the general election. His party won the most seats in December, but not enough to avoid a complicated coalition. Though Spain has seen economic improvement under his leadership, his opponents have been able to portray his leadership as ineffectual because it lost ground in the Catalan issue and because of nagging unemployment. Corruption scandals also cost the party votes. Meanwhile, Podemos topped the polls in the northeastern region of Catalonia in December, dealing a blow to both PSOE and Catalan separatists.
Date written/update: 2016-05-03