Spain’s Constitutional Court left separatists in Catalonia with little choice but to either accept no changes in their relationship with Madrid or declare independence unilaterally when it struck down a watered-down vote on Tuesday that had been called by regional president Artur Mas.

The central government in Madrid had asked the court to block the “consultation” Mas called last month after it earlier suspended a formal referendum, arguing that the vote, which was due to take place on Sunday, was a thinly disguised way to get around the original ruling.

Tens of thousands of Catalans were expected to take to the street to protest the decision. Civil movements and some townhalls pledged they would organize an “unofficial” ballot anyway.

Mas had argued that local elections due in November 2016 could be brought forward and turned into a de facto referendum on whether or not Catalonia wanted to secede from Spain. The two largest parties in its regional legislature, Mas’ conservative Convergence and Union and the less compromising Radical Left, both support independence.

Convergence and Union could possibly be satisfied with increased autonomy for what is Spain’s richest region but the central government’s refusal to even discuss a devolution of powers has radicalized the separatist movement.

Many Catalans feel they are bearing the brunt of Spain’s economic crisis. The region accounts for 16 percent of the country’s population but more than a fifth of its economic output, giving it an economy the size of Denmark’s. An estimated $21 billion in Catalan taxes, equivalent to 8 percent of the region’s gross domestic product, is invested in other parts of Spain.

Polls show some 80 percent of Catalonia’s 7.5 million inhabitants want a referendum while support for independence has surged in recent years, from 13 percent in 2005 to 45 percent this year.