Editor’s note (February 15th 2019): On February 15th Pedro Sánchez, Spain’s prime minister, called a general election for April 28th. This piece, from February 14th, explains why.

T HE NOTION that Pedro Sánchez could govern his country for long without calling a general election always seemed unlikely. He came to office as prime minister unexpectedly last June following a censure motion against his conservative predecessor, Mariano Rajoy. But his socialist party has only 84, or 24%, of the 350 seats in Congress. The alliance of leftists and Basque and Catalan nationalists that backed his minority government was united chiefly in rejecting Mr Rajoy. On February 13th Mr Sánchez’s government seemed to run out of road when its budget was rejected, by 191 votes to 158. On February 15th the prime minister is due to announce if—and more likely when—he will call a general election.

It would be the third time in little more than three years that Spaniards have been called upon to vote. The past two elections produced hung parliaments and weak governments, and the same outcome seems inevitable this time around. Indeed, politics has become even more fragmented with the recent rise of Vox, a far-right nationalist party which is poised to enter parliament for the first time.

What doomed Mr Sánchez, as in part it had done Mr Rajoy, was the conflict in Catalonia, where almost half of voters support independence. By chance, the budget debate coincided with the start of the oral phase of the trial of 12 separatist leaders who face charges of rebellion and misuse of funds for organising an unconstitutional referendum followed by an illegal declaration of independence in October 2017.

Mr Sánchez attempted to defuse the Catalan conflict, talking to the separatist government in Barcelona about their more everyday grievances. The budget included an 18.5% increase in public investment in Catalonia. Rejecting it would be “a historic mistake which you will have to explain to Catalans”, María Jesús Montero, the finance minister, told separatist legislators during the parliamentary debate.

But the 17 Catalan nationalist deputies joined the opposition to vote it down nonetheless. Partly because of the emotive climate generated by the trial, as a condition for backing the budget their leaders had insisted that Mr Sánchez agree to talks with an international mediator about self-determination in Catalonia. In what was Mr Sánchez’s biggest mistake in his short time as prime minister, he dallied with that proposal, agreeing to inter-party talks in Catalonia with an external “rapporteur”. That was not enough for the separatists, but opponents seized on it as a concession to the independence movement’s long-standing demand to “internationalise” the Catalan conflict. Mr Sánchez swiftly retreated, breaking off contact with the separatist administration in Barcelona.

An independence referendum is legally impossible without amending the constitution, a cumbersome procedure. And it is a political non-starter: the vast majority of Spaniards and many Catalans reject the separatists’ attempt to break up their country. International law does not recognise a right to self-determination in an advanced democracy. The government insisted this week that it would not trade the budget for a referendum.

In a febrile political atmosphere the three right-of-centre parties held a rally in Madrid’s Plaza Colón on February 10th at which some 45,000 people, many waving Spanish flags, turned out under the slogan “For a United Spain—elections now”. Pablo Casado, who replaced Mr Rajoy as leader of the conservative People’s Party in the summer, has operated in hyperbolic gear ever since. This month he has called Mr Sánchez a “traitor”, “liar” and “felon”.

Mr Sánchez has said several times that if his budget was rejected, that would shorten the life of the parliament, which in theory runs until June 2020. The betting in Madrid is that he will go to the country in April. If so, he will doubtless try to make the budget, with its modest increase in spending, social provision and taxes, the main issue in an old-fashioned left-right battle. His government was notable for its feminism (more than half of his cabinet are women) and for his determination that Spain should play an active international role. But a spring election would take place against the background of the Catalan trial. Most of the defendants claim that they are political prisoners. The prosecutor argues that they are being judged for their actions, not their ideas. The opposition would try to make the election about defending the constitution and keeping Spain together.

Opinion polls give five parties between 10% and 25% of the vote. Mr Sánchez is an effective campaigner. But at the outset, the most likely outcome is a right-of-centre coalition, backed by Vox. Some of the separatists have long claimed, implausibly, that their battle is against Spanish “fascism”. With their parliamentary vote this week, they seem to want to bring some semblance of that into being.