MADRID — Catalan independence leaders can expect no red carpet from the rest of Spain if they back down from demands for self-determination and decide to settle for increased autonomy.

Although ousted regional President Carles Puigdemont tried to put that option back on the table this week, in an interview from self-imposed Belgian exile, Spain's other regions are wary that ceding to further demands from the highly decentralized Catalans could be detrimental to their own constituencies.

That raises the question of whether the rest of Spain is prepared to offer a deal that at least some Catalan independence supporters would be willing to accept.

“Spain is probably the most decentralized country in the world,” said Manuel Jiménez Barrios, the Socialist vice president of Andalusia, the most populous region of Spain — a view widely shared across the right-left divide. “Andalusia won’t allow any agreement that harms this region and therefore the ensemble of Spain.”

“We shouldn’t raise disproportionate expectations, because the competencies (of the regions) are already very high and it’s difficult to see what else can be decentralized,” said Cristina Cifuentes, president of the richest region, Madrid, and a member of Prime Minister Mariano Rajoy’s conservative Popular Party.

From Valencia on the eastern coast, Socialist regional President Ximo Puig said a red line for a resolution to the Catalan conflict should be that the distribution of power between Madrid and the region "doesn’t generate inequality.”

“It’s a trade-off. The more fiscal autonomy you have, the less capacity for wealth redistribution you get" — César Colino, politics professor at UNED University

Regional leaders are key to finding a negotiated solution on Catalonia, be it to change the constitution to amend Spain's territorial architecture — the subject of a Congress commission to be launched Wednesday — or to reach multilateral agreements on financing, which has long been a Catalan grievance.

Puigdemont and other Catalan leaders have repeatedly signaled their readiness to negotiate with Madrid on a new status within Spain; indeed, Puigdemont's party — PDeCAT — only embraced secession after the central government rejected Catalan demands for a new financial settlement in 2012.

Rajoy has so far rejected such attempts at negotiation, preferring to force the Catalans into existing legal forums for discussions with the regions, in which Puigdemont has refused to take part. In the view of Rajoy's government, Puigdemont and his allies are simply trying to blackmail the entire country.

Behind the rift is a battle for leverage. Catalan leaders reject sitting at the same table as the other regions because they know their proposals wouldn't be welcome, whereas Rajoy doesn't want to treat the Catalans more favorably than anyone else.

The way government spokesman and Cabinet minister Íñigo Méndez de Vigo puts it is that “there is space to talk,” though he rules out accepting any rule-breaking by the Catalans “if we don’t give them what they want.”

Spain for status quo

Rajoy's decision to schedule a Catalan regional election on December 21 will be an opportunity to see exactly how much leverage the separatist leaders have to push on for independence or try to negotiate more autonomy — even though many of Puigdemont's aides and allies are now in custody in Spain accused, as he is, of rebellion.

That could hinder (or perhaps boost) their chances of renewing or improving the absolute majority that pro-independence parties won in the last regional election in 2015 (in terms of seats in the regional assembly, though not as a percentage of votes). Rajoy has urged Catalan voters to punish the secessionist politicians when they vote.

Two senior officials in the two leading Catalan pro-independence parties said that if the secessionist camp fails to win more than 50 percent combined, they'll need to rethink their strategy. They disagreed on whether they should seek a compromise with Madrid or focus on the long-term goal of independence if they fall short of a majority, which some polls currently forecast.

If it's the former option, then the voices of the rest of Spain's 17 autonomous communities or regions — each with its own parliament, government, regional statutes and varying degrees of devolved powers in areas such as health care, education, civil law, culture and policing — will become an essential part of the debate.

Only two other regional presidents — from the Basque Country and Navarre — defend the right to self-determination, but they show little appetite at present to pursue a secessionist agenda of their own.

Among Spaniards at large, about 39 percent of the population is comfortable with the territorial status quo, according to the latest survey by the Center for Sociological Research, while 28 percent would prefer less or no regional autonomy. Just 13.4 percent would like to see increased autonomy and only 10.2 percent favor letting independent-minded areas separate from Spain.

Moreover, the only national party to endorse the right to self-determination and side with the Catalan demands for a referendum on secession, the far-left Podemos, has suffered a big drop in support in opinion polls in the past two months, coinciding with the Catalan conflict becoming the Spanish public's second biggest concern after unemployment.

The liberal Ciudadanos party, which has long taken a more hawkish stance — for instance, it advocated direct rule as a response to Catalonia's defiant unilateral declaration of independence much sooner than Rajoy did — has seen its support rise spectacularly in most surveys. Ciudadanos called for direct rule even before the declaration of independence.

How much is enough

On top of that, there’s the question of what extra powers should be given to the regions. According to the Regional Authority Index, an international database measuring the degree of decentralization for a number of countries, Spain is the second most decentralized country in the world, below Germany but above Belgium, the United States, Switzerland and Canada.

The index measures the degree of decentralization across all territorial levels, including provinces. The research also ranks individual regions, showing different degrees of autonomy within Spain: So Navarre, which levies its own taxes and then negotiates fiscal transfers bilaterally with Madrid, ranks first. It is beaten only by Germany's Länder, the Swiss cantons and the Australian states, and ranks above Quebec, U.S. states and Scotland.

Catalonia, which doesn’t enjoy the fiscal autonomy granted to Navarre and the Basque Country for historic reasons, ranks in the top tier, behind Quebec and the U.S. states but above Scotland and Wallonia in Belgium. The lack of fiscal autonomy is one of the biggest complaints among Catalans, who argue that they pay too much in taxes to sustain poorer regions of Spain.

While Navarre and the Basque Country jointly account for nearly 8 percent of Spain's economic output, Catalonia alone represents 19 percent of GDP — meaning that granting it the same financial status as the Basques would have far-reaching economic implications for the entire country.

“It’s a trade-off,” said César Colino, a politics professor at UNED University. “The more fiscal autonomy you have, the less capacity for wealth redistribution you get.”

Colino argued Spain’s regional redistribution isn’t as powerful as that of Germany, but much stronger than in the U.S., for example. The Spanish particularity, Colino said, is that two of the wealthiest regions – the Basque Country and Navarre — don’t share the costs of redistribution, which forces other rich regions like Madrid and Catalonia to assume the extra burden.

“I believe we need to appreciate more our diversity, which is enriching" — Valencia's Socialist regional President Ximo Puig

Madrid's GDP per capita — the highest in the country — is double that of Extremadura — the lowest. Catalonia’s is 75 percent higher than that of Extremadura.

Eurostat figures show that regional differences between rich and poor in Spain are lower than in Italy and the U.K. — the latter due to the disrupting role of London — and more or less the same as in France (without taking into account the overseas departments) and higher than in Germany (without the role of city-states such as Hamburg).

Yet not all potential areas for territorial reform are as prone to controversy as the financial system. The Spanish Senate, the upper house of parliament, for example, has been the target of widespread criticism over the years and many on the left and right agree that it is due for reform.

Sandra León, senior lecturer in politics at the University of York, said the mechanisms for the regions in Spain to influence decision-making at the central level is one of the weaknesses of the country’s territorial structure — a problem stemming from the limited powers of the Senate, which isn’t the kind of territorial chamber that the Bundesrat in Germany is.

Solving other Catalan nationalist grievances won't necessarily have a high cost for the rest of the country, but will face cultural obstacles that reflect on the divide between the 59 percent of Spaniards who live in regions where only Castilian Spanish is spoken and the rest who live in bilingual regions: The country also has Galician, Basque and Catalan languages.

Catalan, for example, is the main language of education and administration in Catalonia, but it isn’t spoken in the Spanish Congress or the European Parliament. Furthermore, most children in other regions of Spain don’t have the chance to learn it at school.

Yet divisions over such issues are common, even within parties. Whereas Andalusian Socialist Jiménez Barrios didn’t support the idea of lawmakers speaking languages other than Spanish in the national parliament, Socialist Puig from Valencia — a bilingual community — said he did, adding that the whole country should favor the teaching of regional languages in schools.

“I believe we need to appreciate more our diversity, which is enriching,” Puig said.