BARCELONA, Spain >> Scores of Catalan farmers on tractors rumbled into downtown Barcelona today, driving down the city’s broad boulevards in a show of support for a potentially explosive vote on whether the prosperous region should break away from the rest of Spain and become Europe’s newest country.

The Spanish government and secession-minded authorities in the northeastern Catalonia region were on a collision course, with the independence referendum still slated for Oct. 1 despite efforts by the courts and police to stop it.

The tractors carried the Catalan pro-independence flag, called the “estelada,” to the office of the national government’s representative in Barcelona. Similar tractor protests were being held across Catalonia. The region’s biggest farmers’ union said the demonstrations were part of their fight for “democracy and liberty.”

With weeks of antagonism and tension coming to a head, neither side was showing signs of backing down from a confrontation that has pitched Spain into a political and constitutional crisis.

The Madrid-based Spanish government has maintained the ballot cannot and will not happen because it contravenes the constitution, which refers to “the indissoluble unity of the Spanish nation.” Any vote on Catalan secession would have to be held across all of Spain, the government says.

“This secessionist process has been illegal from the start,” government spokesman Inigo Mendez de Vigo said today. “Since the referendum … won’t have any political consequence, pursuing it won’t do anything but extend the damage, the harm and the disintegration that it is already doing.”

Acting on court orders, police have confiscated about 10 million ballot papers and some 1.3 million posters advertising the referendum, and have blocked the distribution of ballot boxes.

The Catalan regional government and local civic groups insist they are entitled to exercise their democratic rights and intend to do so regardless of the obstacles. Their grievances include what they say is Madrid’s ignoring of the region’s long-standing demands for a greater degree of autonomy and fiscal powers. With Barcelona as its regional capital, Catalonia contributes a fifth of Spain’s 1.1 trillion euro ($1.32 trillion) economy.

On Friday, the Catalan government unveiled white plastic containers it said would be used as ballot boxes. More than 2,300 polling stations would be set up for 5.3 million voters, Catalan government spokesman Jordi Turull said.

“Everyone can stay calm, because we’ll be able to vote,” Turull said.

The government in Madrid ridiculed the preparations, saying there had been no formal campaign period and no electoral roll.

Barcelona has witnessed large street demonstrations in favor of the ballot for weeks. Jordi Marti, a 63-year-old Barcelona taxi driver, has plastered his vehicle with stickers supporting the vote, saying the central government has kept Catalonia in a chokehold for too long.

“And now we have said, ‘Game over,’” he told The Associated Press. “It’s over because we have been negotiating with the Spanish government for 40 years … and it hasn’t been worthwhile.”

The noisy demonstrations have largely drowned out opponents of independence, with hardly any counter-demonstrations in favor of remaining part of Spain. While opinion polls have indicated the vast majority of Catalans favor holding a referendum, they are almost evenly split over independence itself.

Catalan leaders, including regional President Carles Puigdemont, said Sept. 28 that senior European Union officials should step in and broker a political solution to the stalemate.

But European Commission Vice President Frans Timmermans appeared to scotch that idea, saying today that the constitution must be respected.

“That is the rule of law — you abide by the law and the constitution even if you don’t like it,” he said.