WASHINGTON—On September 11, 2012, a tsunami hit Spanish politics. Months of independence marches through small Catalan towns and villages culminated in the heart of Barcelona, when as many as 1.5 million people —over 22 percent of Catalonia’s population — took to the streets under the banner “Catalonia: A New European State.” The march came just as some polls recorded that, for the first time since the 1970s, the majority of Catalans would vote for independence from Spain.

The reasons for this shift within Spain’s most economically prosperous region have been accumulating for years: the crippling financial crisis, resentment over transfers of roughly 8 to 9 percent of Catalonia’s GDP to poorer regions of Spain, the 2010 evisceration by the Spanish Constitutional Court of an enhanced Catalan statute of autonomy, and a lingering concern that Madrid is unable or unwilling to sufficiently appreciate the richness of Spain’s plurality.

Yet if the Barcelona march rattled Madrid, it had seismic effects on Catalan politics. First, it helped persuade the ruling center-right Convergence and Union (CiU) coalition — which has governed Catalonia for 25 of the last 33 years on a moderately nationalist platform, preferring always to push for greater autonomy rather than outright independence — to do an about face. In late September, when denied his request for a new fiscal pact with Madrid by embattled Spanish Prime Minister Mariano Rajoy, Catalan President Artur Mas stunned the country, and Catalan nationalists, by dissolving the regional legislature. He called for new polls, asking the Catalan people to give CiU an “indestructible majority” to hold a referendum on Catalonia’s future within four years. It was a two-fold lurch into uncharted waters. Suddenly CiU had appeared to become a secessionist party, and the Catalan nationalist movement had been offered an actual referendum on splitting from Spain. Catalan elections, expected in 2014, were moved to November 2012, and Mas’ visibility in Spain, as well as Europe, began a sudden, meteoric rise.

However, on November 25 CiU dropped from 62 seats in the 135 seat Catalan Parliament to 50, its worst showing since 1980. Instead of earning an absolute majority, Mas was granted at best four shaky years of minority rule. In Madrid, Rajoy broadsided the Catalan premier, saying that he had never seen as ruinous a political operation as Mas’. Spanish pundits explained the outcome by pointing to the success of the pro-unionist Citizens Party, which tripled its representation from 3 seats to 9, and the modest gains for Rajoy’s conservative Popular Party (PP), which rose from 18 seats to 19.

It is true that Mas miscalculated in thinking he could appropriate the cresting wave of Catalan patriotism for CiU. But Rajoy also risks missing the bigger picture. Almost two-thirds of the votes in the election went to nationalist parties in favor of a referendum, with the largest gains going to the Catalan Republican Left (ERC), a fiercely pro-independence party. Catalan nationalists viewed Mas’ abrupt and still murky pro-independence turn with suspicion, and many voters in favor of independence flocked instead to ERC. The fear among many was that Mas viewed the proposed referendum as a bargaining chip for his real goal, fiscal autonomy. And while Mas, despite his shift, still hesitates in using the actual term “independence,” ERC has had no such reservations. Alfred Bosch, leader of ERC in the Spanish Parliament, displayed the Catalan secessionist flag with combative flair during a recent parliamentary speech in Madrid.

So while Catalan nationalists have temporarily been denied a clear figurehead to drive their cause boldly forward, the wind is not entirely out of their sails. ERC will continue to oppose CiU on economic grounds — it was a vociferous opponent of the three recent austerity packages pushed through by the Mas government, with close support of the PP. But it will unwaveringly push for a referendum process that is no longer controlled by Mas. The plebiscite, and a potential constitutional crisis in Spain, will if anything come sooner now than had Mas and the CiU triumphed.

In a recent interview, Spanish Justice Minister Alberto Ruiz-Gallardón said “People talk about Catalonia as if it was a limb that could be amputated and the rest of Spain would survive….But what the independence of Catalonia really means is the disappearance of Spain as a nation.” Rajoy, along with many other leaders in pluralistic European states, will hope that CiU’s slide signifies the beginning of a nationalist decline in Catalonia. And perhaps the region will follow the path of Quebec, where a landmark referendum in 1995, in which the pro-independence vote fell just short of a majority, deflated the Quebecois independence movement. Yet the reconfiguring of Catalan politics could just as likely mark the deeper entrenchment of secessionist sentiments, with leaders less willing to compromise now gaining ascendancy. Policymakers on both sides of the Atlantic would do well to keep a close eye on the swirling politics of Catalonia.

Nicholas Siegel is Senior Program Officer with the Transatlantic Academy, an initiative of the German Marshall Fund of the United States in Washington DC.