Spanish election: Socialists battle to stop right-wing surge

Spain holds its third general election in four years on 28 April, in a battle between the established parties, Catalan and Basque nationalists, and a rising far-right.

This time, however, the electoral game has changed.

Support for the previous winner, the conservative People's Party (PP), has collapsed amid a corruption scandal. Its main opponent, the Socialist party, has rocketed to the top of the polls after seizing the prime minister's job last year.

Podemos on the left and Ciudadanos (Citizens) on the right are seeing their support fall, amid a boom for the controversial far-right Vox party.

One recent poll showed almost half of voters - 40% - had yet to make up their minds.

What are the possible outcomes?
Opinion polls may not tell the full story, particularly with so many undecided voters. But the potential outcomes for a government include:

Socialists, left-wing Podemos, plus small nationalist parties
Centre-right PP, liberal Ciudadanos and far-right Vox
Socialists and Ciudadanos
But there is a problem with each of these combinations.

The Socialist and Podemos alliance of Prime Minister Pedro Sánchez's existing government needed the Basque and Catalan nationalists to support it.