Spanish Prime Minister Pedro Sánchez of the Socialist Party (PSOE) waves to supporters during a campaign rally Thursday in Barcelona. (Pau Barrena/AFP/Getty Images)

On Sunday, Spain will hold an election for its parliament, which will then choose a new government.

This is the third time that Spaniards have voted in national elections since 2015. After the first of these elections, parliament could not agree on a government, so a repeat election was held in 2016. After that, parliament selected Mariano Rajoy of the conservative Popular Party as prime minister — but only because the main opposition Socialists abstained. With only 39 percent of seats in parliament, the Popular Party formed a single-party minority government, with support from a new center-right party, Citizens.

The conservative government did not survive long. In May 2018, a court ruled that the Popular Party had benefited from an illegal kickback scheme in the early 2000s. In June 2018, the center-left Socialist Party (PSOE) rallied opposition parties to bring down the government in a vote of no confidence.

The no-confidence vote brought the Socialist Party into power, and Prime Minister Pedro Sánchez formed a single-party minority government. The Socialists held only 24 percent of the seats in parliament. This government will be even more short-lived than the last one. After parliament rejected the government’s budget bill in February, Sánchez called the early elections that will take place this Sunday.

Both governments struggled to accomplish their political agendas and pass budgets — and, clearly, failed to survive.

That’s new in Spain. Its previous governments were among the longest-lasting in Europe. They generally accomplished their political priorities, regardless of whether they governed with a majority.

The Sunday elections are set to fragment parliament further, complicating the formation of a new government — and raising the question of whether Spain can be governed.

Parties have proliferated in Spain

Before 2015, the Socialist Party and the Popular Party dominated Spain’s politics. Small, often regional parties from Catalonia, the Basque Country and elsewhere gave support to governments when they did not have majorities. This made Spain governable.

Things have changed. Voters supported new parties in 2015. Podemos (We can), an anti-establishment party to the left of the Socialists, won seats in parliament. So did Citizens, a party that campaigned on political renewal. Citizens started as a center-right party opposed to Catalan nationalism; it stresses that it will defend a single Spanish nation. In contrast, Podemos’s vision accommodates Spain’s multiple national identities.

Parliament will fragment even more after the coming election, particularly on the right. Polls project that a far-right party, Vox, will win seats for the first time. Spain had stood out from other European nations trending right because it did not have an electorally viable far right. No longer.

Much like its European counterparts, Vox is nativist and anti-Islam. But its lifeblood is Spanish nationalism, opposing Spain’s own peripheral national identities and the Catalonian push for independence. It supports political centralization, conservative values and right-wing economic policies. It resolutely opposes feminism, which it calls “gender ideology” — and wants to repeal Spain’s laws against gender violence. Citizens and the Popular Party also have moved further right.

These are the first national elections since the failed push for independence by Catalan secessionists in October 2017. While Spain is beyond the peak tension of the Catalan crisis, several political and societal leaders are in prison and on trial for related charges, including rebellion, sedition and misappropriation of funds. Catalonia and territorial and national-identity questions have dominated the election campaign.

The election’s outcome is more uncertain than usual

Polls have the Socialist Party with a secure lead of about 30 percent of the vote. The Popular Party, with 20 percent; Citizens, with almost 15 percent; the Podemos alliance, with 14 percent; Vox, with 11 percent; and other small and regional parties follow. However, the outcome remains highly uncertain.

Voters are far less loyal to parties than they have been in the past. Voters on the right, in particular, are wavering about whether to vote for the Popular Party, Citizens or Vox. Spain’s most comprehensive pre-election survey estimated that as many as 42 percent of voters were undecided. And turnout matters. What’s more, in districts that elect few legislators, small changes in the vote can greatly affect which parties win seats.

So, much like the previous parliament but more so, the new one will be fragmented and even more polarized. This time, however, there is little chance there will be a single-party cabinet. The newer parties will probably demand cabinet positions. A coalition government would be a novelty; Spain has had only single-party national cabinets since democracy returned about 40 years ago.

There are several possible governments. Based on polls, the most likely is a leftist coalition government of the Socialist Party and Podemos, possibly with support from regional parties in parliament. This government may need support from Catalan secessionist parties, as has been true for the current Socialist government. Such a government would face constant criticism from the political right for what it views as selling out to secessionists — which has plagued the Sánchez government.

A second possibility is a coalition between the Socialists and Citizens with a centrist policy agenda, yet unclear effects on how Spain will manage its severe territorial divisions, especially Catalonia. But Albert Rivera, the leader of Citizens, has repeatedly ruled out governing with Sánchez’s Socialists. This makes an about-face costly, if results allow for it.

A third possibility is a right-wing government of the Popular Party and Citizens, in which the far-right Vox either supports or (less likely) enters the government. There is a precedent. Earlier this year, Vox supported the Popular Party and Citizens as the latter two formed a government in Andalusia, Spain’s largest region. The three parties have focused their campaigns on Spanish national identity and opposition to Catalan secessionists, whom they view as having perpetrated a coup against Spain. They have threatened to suspend Catalonia’s autonomy again.

The day after

Regardless of the outcome, choosing a government will take time. Political parties will want to wait until after the regional and local elections on May 26. In Spain’s decentralized political system, political parties often exchange support across territorial levels — local, regional and national. Plus, the ongoing trial of Catalan independence leaders will influence their willingness (and that of their voters) to support a leftist government.

This leaves, of course, a fourth possibility: failure to form a government, and new elections.

Bonnie N. Field is professor of global studies at Bentley University in Massachusetts and the author of “Why Minority Governments Work: Multilevel Territorial Politics in Spain.”

Juan Rodríguez-Teruel is professor of political science at Universitat de Valencia in Spain and the author of “Los Ministros de la España Democrática.”