This Sunday, Dec. 20, Spaniards will go to the polls in one of the most unpredictable elections since the country’s transition to democracy in the late 1970s. For the last three decades Spain’s politics have been dominated by the conservative Popular Party (PP) and the Socialist Party (PSOE). Now for the first time, the centrist Citizens and the leftist Podemos, or We Can, parties are challenging the two dominant organizations.

One thing is certain: The day after the election the next prime minister will be forced to address the question of Catalan secession. In Catalonia, a northern Spanish region that makes up 16 percent of Spain’s total population and produces 19 percent of its total gross domestic product, pro-independence parties are pushing ahead with a historic plan for an independent state.

Since the onset of economic crisis in 2008, nationalist politicians in Catalonia have increasingly clamored for independence. In the regional elections of September 2015 Catalan nationalist parties won an absolute majority of seats (though not votes) in the 135-seat regional assembly. Last month this majority, led by regional governor Artur Mas, approved a measure in the Catalan parliament to formally begin the process of breaking away from Spain. The parliament outlined a plan for the region’s independence by 2017.

The Madrid government challenged the resolution in the Constitutional Court, which suspended the motion and declared it unconstitutional. Grounded in this legal position, Spanish Prime Minister Mariano Rajoy’s argument to the Catalan secessionists has been simple: Spain’s constitution forbids such a referendum, so don’t do it. This position has been matched by a similar position from Albert Rivera, leader of the centrist Citizens party, which looks poised to emerge as a powerful political force in Sunday’s general election.

The socialists of PSOE have also rejected a referendum on independence, but have proposed a constitutional reform in the next legislature to transform Spain into a truly federal system. But Podemos has committed itself to an independence referendum in one year, arguing that Catalonia has a legal right to decide, and proposing a new constitutional definition of Spain as a ‘pluranational’ state (see table).

Based on the same simulations used to predict seat totals in the table, political analyst Kiko Llaneras (EL ESPAÑOL) predicts that PP and Ciudadanos will together have a 76 percent chance of receiving the 176 deputies necessary to form a majority coalition, while the PSOE, Ciudadanos and Podemos together will have a 91 percent chance of reaching the necessary number of 176.

However, considering their divergent views on the Catalan issue, it’s not as likely that the latter group could agree on a common strategy. Put differently, it would not be surprising to see a PP-Ciudadanos coalition as the outcome of this Sunday’s election.

What would that mean for the Catalan issue? And what about the less likely but nonetheless possible three-party coalition without PP? We believe bargaining theory will provide useful insight.

The dangerous game of chicken

Why have Rajoy, Albert Rivera and other Spanish unionists adopted such a staunch bargaining position? And why have Artur Mas and his secessionist colleagues done the same? This has all the hallmarks of a ‘game of chicken,’ one of the classic strategic frameworks used to understand international bargaining.

As anyone familiar with James Dean knows, in the game of chicken two individuals drive automobiles directly at one another, with the goal of making the other driver ‘flinch.’

In his 1960 famous book “The Strategy of Conflict,” Nobel-winning economist Thomas Schelling noted the importance of commitment mechanisms, such as tying one’s hand to the steering wheel so as to take the possibility of flinching out of one’s possible set of actions. The national government may feel that legal rulings by the constitutional court provide exactly such a credible commitment to a hardline, no-referendum position. It essentially eliminates the central government’s ability to flinch.

On the other hand, strategic theorists unanimously agree that hardball strategies in games of chicken imply lots of risk. The other side may call your bluff. The Catalan secessionist movement has also adopted increasingly intransigent strategies, going as far to adopt legal measures which they themselves may see as credibly locking them in to an uncompromising stance. Research by Robert Powell, James Fearon, and others suggests that oftentimes these games end in outright conflict. In most situations it is difficult to identify which side has an advantage.

Some factors do seem to benefit parties engaged in a strategic negotiation, as explained by economics professor Abhinay Muthoo. Patience is one. Another is having better outside’ options: being able to credibly leave the bargain, revert to a status quo or withstand the negative consequences of conflict. Patient bargainers with better outside options are likely to have the advantage, which tilts negotiations in their favor.

In the Catalan question, do considerations of ‘patience’ and ‘outside options’ benefit one or the other party? This is difficult to assess. Unionists may have been emboldened by recent statements from Brussels and senior European Union civil servants that if Catalonia secedes it will have to leave the European Union and re-apply for membership. This seems to restrict the Catalan nationalists’ outside options, such as their chance of political and economic integration, in the event that they attempt to secede. One might also think that time is on the central government’s side: As the stronger party in the negotiation, if it simply waits out the worst of the economic crisis, the nationalist fervor may fade.

Or time may be on the nationalists’ side. Survey data demonstrates that support for independence in Catalonia has increased since 2010. The latest poll by the Catalan Government’s Survey Institute (CEO) showed that 46 percent favor independence while 48 percent of Catalan citizens oppose. Previous research has shown that about 15 percent of supporters of independence have only shifted recently into the secessionist camp. Analysts have called them ‘disenchanted federalists.’

Perhaps even more damning for the unionist cause is the distinct possibility that the PP’s hard line in negotiations may explain at least some of the rise in secessionist sentiments. Adopting harsh policy positions against refugees and immigrants can give them just the ‘push’ they need into radicalism. By a similar logic, the uncompromising attitude adopted by some unionists may strengthen the secessionists’ argument that the Spanish state is repressive and worth leaving, thus winning over more Catalan voters.

The correlation exists, as documented by Ignacio Sánchez Cuenca (in Spanish) and others. But there is causality problem here. How are we to know whether or not a central government hard line leads to more secessionism in Catalonia, or vice versa?

Regardless of why, if a large majority of the Catalan population ends up backing secession, then the maintenance of territorial integrity will need to be imposed, perhaps even using non-conventional means. Is the threat of outright coercion or force credible? Despite its recent statements, would the European Union allow extreme coercion? If Catalonia does manage to secede, would the E.U. be tempted to allow it in because of Catalonia’s wealth?

Moving beyond chicken

There is, of course, an alternative to stalemate. As of now popular support for independence within Catalonia is, by most accounts, less than 50 percent. But it has been rising. Now may be an opportune moment for the next central government to make a concessionary offer that could lead to some measure of reconciliation.

One agenda-setting strategy would be to offer the Catalan secessionists a choice between the proposals being made by the Socialists of PSOE (a constitutional amendment transforming Spain into a truly federal system) and the upstart Podemos (the opportunity to organize a binding referendum).

The Catalan parliament and secessionist movement would then have to decide whether to take the federalist offer or organize a referendum. Since support for secession within Catalonia has been rising, it might seem that they have every reason to reject the federalist offer and hold the referendum. But that would depend on how fast support rises. Furthermore, without the marketing benefit of an intransigent central government, the secessionists may lose their best recruiting tool and see fewer Catalan voters pushed into the secessionist camp via “disenchanted federalism.”

In other words, if they are strategic and rational, Mas and colleagues may end up preferring a federalist amendment to either a current referendum (which they would most likely lose), or to an ongoing negotiation without the recruiting benefits of an intransigent government in Madrid. Oddly enough, the secessionists’ best hope for genuine independence may be that the situation stay stuck long enough to push enough Catalans into the independence camp.

Of course, many unionists see concessions as a non-starter. In the event that the outcome of Sunday’s election is a Ciudadanos-PP coalition, the risky game of chicken will likely continue. On the other hand, if a distinct coalition emerges compromise may be more likely. Only time will tell.

Daniel Kselman is professor and academic director at the IE School of International Relations (IE University), and is also president of the Minga Foundation.

Jose Piquer is director of the bachelor of international relations at the IE School of International Relations (IE University). He blogs here and tweets @josepiquerm.