Spain's Prime Minister Pedro Sánchez has called a snap general election for 28 April, after Catalan nationalist MPs withdrew support for the Socialist government's budget.
It is just eight months since Mr Sánchez took office, heading a minority government reliant on Catalan support.
Opinion polls suggest that no single party would win a clear majority. But conservatives and the far-right Vox party are expected to do well.
The Catalan crisis is still simmering.
Catalan separatist MPs rejected Mr Sánchez's budget bill after the government refused to discuss the region's right to self-determination.
Divisions were highlighted on Tuesday, when 12 Catalan separatist leaders and activists went on trial accused of rebellion and sedition over their unrecognised independence referendum in 2017.
The Socialists (PSOE) have 84 seats in the 350-seat lower house (Congress of Deputies), and their main allies, anti-austerity Podemos, have 67. But the biggest party is the conservative opposition Popular Party (PP), with 134.
In his announcement, Mr Sánchez complained that the right-wing parties - the PP and Ciudadanos - had blocked numerous bills in parliament, including important measures to reduce inequality.
Is this snap election unusual for Spain?
Yes. Since the return of Spanish democracy, with the death of fascist dictator Francisco Franco in 1975, it is only the second time that a government's budget bill has been defeated in parliament.
The previous occasion was in 1995, when the Socialists under Felipe González were forced to call an election.
Turbulence and shifting alliances
By the BBC's Guy Hedgecoe in Madrid
While the end of Pedro Sánchez's tenure looked inevitable, following his parliamentary budget defeat, this adds further uncertainty to a fragmented Spanish political landscape.
His PSOE is leading many polls and could win this election, but might find it hard to form a majority and govern.
The leftist Podemos, the PSOE's natural ally, is riven by infighting and struggling in polls.
With the Catalonia issue likely to dominate the upcoming campaign, the hardline pro-unity stance of parties on the right - the PP and Ciudadanos - could see them benefit. If the numbers add up, they could try to form a majority, possibly with the support of far-right Vox, which has enjoyed a surge in polls, due mainly to its uncompromising policy on Catalan independence.
European Parliament snubs Catalan ex-leader
Amid tensions over the trial of his associates, the exiled former Catalan leader Carles Puigdemont has seen an event he was due to address at the European Parliament cancelled on security grounds.
Several Spanish politicians had objected to the presence of Mr Puigdemont, who has fled Spain where he is wanted for alleged crimes linked to Catalonia's failed bid for independence in 2017.
He had been invited by a group including a Flemish nationalist MEP to speak about the trial.
The Parliament cited the tensions around the trial as a factor in its decision, as well as the recent occupation by separatist protesters of a building in Barcelona it uses jointly with the European Commission.