Artur Mas is in buoyant mood. He has just finished preaching to the converted and, for the second time today, has belted out an anthem glorifying 17th-century peasants and warning the enemies of Catalonia to tremble with fear.

But behind the euphoria is a canny pragmatism. Mas, the president of the Catalan Generalitat, is coasting along on a crest of unprecedented support for independence for Catalonia from crisis-ridden Spain. But he's also trying to control it. And he knows it's going to be a giddy journey.

"I have nothing against Spain, absolutely nothing," says the 56-year-old economist, perched on the steps of a makeshift stage from which he addressed a crowd awash with striped Catalan flags. "In many ways I feel that I am a friend – of the Spanish language, of many people in Spain and of many Spanish cultural traditions. But as of many years ago I feel Catalan. I think in Catalan, I don't think in Spanish."

As the financial crisis petrifies across Europe, it is testing the ties that have bound nations together – and nowhere more so than in north-eastern Spain. In September Barcelona witnessed the biggest independence march in Europe since the second world war. That single event transformed Catalonia's long-running quest for ever greater political self-determination.

Polls show the number of those who, like Mas, would vote "yes" to independence has shot up from 43% to 57% in little more than a year. An election on Sunday, 25 November, will serve as a quasi-plebiscite on secession. The Guardian, in collaboration with Catalonia's leading La Vanguardia newspaper, is devoting a week of coverage to the region, asking if secession is a viable or desirable outcome. Even Mas knows it will not be easy.

He has promised a referendum of some kind within four years, but national government ministers in Madrid warn this will be banned. Defiance would be tantamount to a coup d'état, they say. So will he stick to his guns? "There will be a consultation," he insists. Ideally, Mas would ask Catalans an apparently simple question: "Do you want Catalonia to have its own state in the EU?" He would like to strike a deal similar to David Cameron and Alex Salmond's pact allowing for a 2014 referendum on Scottish independence. But the national government of conservative Mariano Rajoy is against that, so he will pass a law through the regional parliament regulating local referendums. "If they take that to the courts and ban it then we will request a degree of protection from European institutions," he says.

"What Europe can do is put pressure on the Spanish government to negotiate," he says, claiming the banning of even a non-binding referendum would violate the EU's democratic values. "There will be a problem that in one part of Europe you cannot express the democratic voice of the people."

Mas has criss-crossed Catalonia in recent weeks, seeking support. This month he travelled north and inland from Barcelona past the jagged outline of the Montserrat, Catalonia's "sacred mountain", to campaign in chilly Manresa, famed as one of the coldest, ugliest city in Catalonia. "He is a man who will go down in history," said Montse Camprubí, director of a home for the elderly in nearby San Fruitós, as well-groomed, middle-aged people packed the hall. The same evening he was in Sabadell, an industrial city near Barcelona, for a noisy rally full of verbal blows against those claiming independence will bring ruin. Youths waved gold and red-striped Catalan flags and separatist banners bearing an added blue triangle and white star. They clearly hoped for an independence that even some in Mas's Convergence and Democracy coalition worry is an impossible dream.

Spain's state pollster has long asked people to define themselves as just Catalan, Catalan-Spanish or just Spanish. Two-thirds now say they feel both Catalan and Spanish, suggesting a halfway solution must exist. But Mas is not one of them. "Just Catalan," he says.

Election posters picture the 56-year-old with his arms outstretched in a pose that wags liken to Charlton Heston's Moses leading his people to the promised land in The Ten Commandments. "He thinks he is on an historic mission," said Joan Saur, a former Catalan minister from the Initiative for Catalonia Greens party. "That is the last thing we need."

"They are trying to divide us, just like in the civil war," tattooed market trader Miguel López complained at his stall amid the high-rise blocks of L'Hospitalet, another industrial city full of families who migrated from poorer parts of Spain in the 1950s and 60s. "That's just stupid. We are all Spanish and we are all Catalan."

That reaction explains why Mas refuses to use the word "independence". It is not in his speeches or in his party's manifesto. Euphemisms such as "our own state" or "structures of state" are used instead.

More ardent separatists suspect he avoids the word because he plans to negotiate a watered-down deal with Madrid, perhaps settling for better financing. But asked to define Catalonia's "own state", Mas admits it is like any other. "It is what Denmark, Finland or Austria have. In the same conditions."

He admits the path forward will be difficult. Many see Spain as inconceivable without Catalonia. The declaration of a Catalan state in 1934 led to armed conflict. And this is virgin territory for an EU that has never seen a member state split up and is wary of opening a Pandora's box of separatist movements and territorial claims.

But Mas says Catalonia will remain peaceful: "It will either be done peacefully, or it won't be done. There won't be violence. There won't be terrorism."

Confrontation with Rajoy suits his party. Aides claimed Rajoy's dark rhetoric would drive moderate Catalans towards him and win over backers of more clearly separatist parties.

Mas's rising popularity is a remarkable turnaround. Only 18 months ago he and his government had to be flown by helicopter into the parliament in Barcelona as angry indignados blockaded it to protest against health and education cuts. So is this just a smokescreen?

"You will not find a single populist measure in our programme. It is evident that I cannot promise that there won't be more cuts, and I explain it like that," he says. Cleverly, he has persuaded voters these elections are about something else.

But he says everything is open, with a wide consensus needed even for agreeing the question in a non-binding referendum that may not be held until 2016. That consensus will be easier to find in Catalonia than Madrid, where conversations would not start until next year. "That is if there are any conversations," he says. "Because it could be that Rajoy simply refuses to talk."