MADRID -- The depth of Catalonia's challenge to Prime Minister Mariano Rajoy should become clear on Sunday, when an early election could help determine whether Spain's most powerful economic region eventually splits from the rest of the country.
The vote comes at a difficult moment for Mr. Rajoy, who stands on the front lines of the euro crisis and is under pressure to decide whether Spain needs more financial assistance through bond purchases by the European Central Bank. Mr. Rajoy is also battling record unemployment and street protests against his austerity measures.
Artur Mas, leader of Catalonia's regional government, called the election two years early after failing to convince Mr. Rajoy to ease Catalonia's federal tax burden, and following a massive pro- independence rally in Barcelona on Sept. 11. That turnout by hundreds of thousands of Catalans has galvanized the region, where the distinctive Catalan flag is on display in shops, bars, and even bare hilltops.
If he triumphs on Sunday, Mr. Mas has pledged to hold a referendum on independence, defying warnings from Madrid that this would violate Spain's constitution.
Initially, Mr. Rajoy tried to combat the Catalan challenge by urging greater national unity and solidarity among Spain's 17 regions. In recent days, however, the prime minister has thrown some of his natural caution to the wind and accused Mr. Mas of acting irresponsibly by turning the vote into a divisive plebiscite on independence and thus diverting Catalans' attention from his own financial mismanagement.
Last Sunday, Mr. Rajoy told a rally in Catalonia that Mr. Mas had achieved nothing except "create divisions, generate conflicts and waste precious time in the fight against the crisis."
Mr. Rajoy also rebutted the idea that independence could give Catalonia's 7.5 million inhabitants greater clout. "To be somebody in today's world, the bigger you are the better, and the smaller the worse," Mr. Rajoy argued.
Still, in a region with its own Catalan language and identity, the current crisis has helped bring longstanding cultural and economic resentments to a boil.
And far from being too small, Mr. Mas is arguing that Catalonia and its €200 billion, or $260 billion, economy could fit comfortably within a European Union that already contains a dozen smaller nations and should in future be coordinated more clearly from Brussels.
In an interview with the International Herald Tribune in October, Mr. Mas suggested Catalonia could become a state comparable to Massachusetts, ideally as "part of the United States of Europe."
While Mr. Rajoy has shown wavering leadership and been forced by deepening recession to break several pledges made when he campaigned for election last year, Mr. Mas has managed to thrust his separatist goal to the top of Spain's domestic political agenda.
Alfred Bosch, a national lawmaker from Esquerra Republicana de Catalunya, or ERC, a party that has long pushed for independence, likened Mr. Mas to someone entering the thick of battle.
"Artur Mas is like a swimmer who is just trying to ride the waves and getting pushed by the current, but is somehow skillful enough to make it look as if he's really a strong swimmer," he said in an interview.
In fact, recent opinion polls show Mr. Mas and his Convergencia i Unió party winning on Sunday, but falling short of an absolute majority in the Catalan Parliament. The eventual outcome is uncertain, depending on the showing of smaller parties, such as ERC, that may or may not ally with Mr. Mas.
Recent surveys show that Catalans remain divided over whether any rupture with Madrid should be limited to fiscal sovereignty, or go beyond that.
Catalonia contributes almost a fifth of Spain's economic output. But the crisis has shone the spotlight on mismanagement by Catalonia's own politicians, which helped its debt balloon to €42 billion of the €140 billion debt of Spain's 17 regional governments. With a junk debt rating, unable to tap financial markets, Catalonia was recently forced to ask Madrid for an emergency loan of €5 billion.
Mr. Mas has cast that not as a sign of Catalonia's weakness but as proof of the need to lower the Catalan contribution to a system that redistributes revenues from richer to poorer regions. Whatever the outcome of Sunday's vote, any subsequent fiscal concession by Mr. Rajoy could go a long way toward deflating the Catalan drive for independence.
For now, the election campaign has turned personal, and vitriolic. Mr. Mas, 56, this week launched a libel action against El Mundo, a conservative Madrid newspaper, over corruption and tax evasion allegations.
"I hope to be the last president of Catalonia whom the Spanish state tries to destroy," Mr. Mas told a rally this week, adding that his successor will in any case "no longer depend on the Spanish state."
This article originally appeared in The New York Times.