ON December 21st Catalans will vote in a regional election, for the fourth time in seven years. But this one is different: it will be closely watched not just in Spain but across Europe, for signs of whether it will mitigate or exacerbate the stand-off between the Catalan independence movement and the government in Madrid. If the separatist block wins an absolute majority of votes it will press even harder for a legal referendum on independence. If it loses its previous majority of seats in the Catalan parliament, that would widely be seen as a victory for Mariano Rajoy, Spain’s conservative prime minister.

The election takes place in extraordinary circumstances. It was called by Mr Rajoy, who was granted previously unused powers under Article 155 of Spain’s constitution to suspend Catalan self-government after a unilateral declaration of independence organised in October by Carles Puigdemont, the Catalan president. This followed an unconstitutional independence referendum on October 1st, in which Mr Puigdemont’s administration said 43% voted amid police violence. Mr Puigdemont is campaigning via videolink from Brussels, where he fled after the independence declaration. He faces arrest on charges of rebellion if he returns to Catalonia. Oriol Junqueras, the leader of Esquerra Republicana (Republican Left), the largest separatist party, is in jail, facing a similar charge. In all, eight pro-independence candidates are either in prison or self-exile.

The demand to free its leaders has reinvigorated the independence movement. Some supporters were disillusioned when no European government backed their cause and almost 3,000 Catalan companies moved their domicile because of Mr Puigdemont’s actions. With Catalonia split almost evenly between two warring blocks, the outcome of the election depends mainly on turnout. Pollsters think more than 80% will vote, including some previously apathetic anti-independence voters. The opinion polls suggest the three separatist parties may just squeak a majority of the 135 seats in the Catalan parliament (in 2015 they won 72). They think Ciudadanos (Citizens), a newish centre-right party which is passionately opposed to independence (and one of whose rallies is pictured), will win most votes, but only 23% or so. Almost equally important will be who comes top on the separatist side, Mr Puigdemont or Esquerra. Mr Puigdemont, who belongs to the Catalan Democratic Party (PdeCAT), is campaigning for the restoration of his administration. For this election he has insisted on choosing his own non-party “President's list”, which is fighting under the heading Junts per Catalunya (Together for Catalunya). In 2015 PdeCat and Esquerra ran as a joint coalition, winning 62 seats and getting a majority thanks to third-party support. Esquerra refused to repeat the exercise this time.

With seven parties likely to win seats, forming a new Catalan government will be hard. If Mr Puigdemont wins, Mr Rajoy will face pressure from his supporters to move to direct rule, escalating the confrontation. More likely outcomes are a more moderate separatist government, headed by Esquerra; or a centre-left coalition comprising Esquerra; the Catalan affiliate of Podemos, a left-wing party; and perhaps the (anti-independence) Socialists. Some of Esquerra’s leaders say they would set aside independence as a long-term goal and concentrate on governing. In any event, the election is likely to be followed by weeks of haggling. And the Catalan problem will continue to bedevil Spanish politics, even if it mutates from acute to chronic.