In more than 900 towns across Catalonia, an army of volunteers is preparing to open polling stations Sunday and offer compatriots a vote on independence in defiance of Spain's central government and its highest court.

The informal ballot, stripped of legal validity by a constitutional court ruling in September, poses two questions: Do you want Catalonia to be a state? And should that state be independent? Separatists led by regional president Artur Mas aim to win a majority in favor of breaking up Spain and use that mandate to force Prime Minister Mariano Rajoy to negotiate.

The runup to the vote has been marked by legal salvoes: Rajoy's government reminded public officials in Catalonia of their obligation to respect the constitutional court ban as Mas had an appeal to that ruling thrown out by the Supreme Court. The Catalan government talked of filing a lawsuit against Spain in an international court while an activist group in Madrid responded with its own suit to state prosecutors demanding police halt the balloting.

"The Spanish government is being really short-sighted," said Alex Quiroga, a lecturer in Spanish history at Newcastle University in England. "Continually saying 'no' and appealing to the constitutional court doesn't help. It's clear that only through negotiation can they solve the problem."

Thousands of Catalans are ready to set up ballot boxes across the region in the expectation that perhaps millions will cast their ballots.

Catalonia is home to 7.4 million people in the northeast corner of the Iberian peninsula. It has the largest economy of Spain's 17 autonomous regions: an annual output of 193 billion euros. That's about the same as Finland or Scotland, where in September voters opted to remain part of the U.K. in an independence referendum.

Diplocat, a public diplomacy association funded by the government of Catalonia and private companies, invited a group of eight European lawmakers to observe the vote. Ian Duncan, a member of the European Parliament for the U.K. Conservative Party, which supported Scotland remaining part of the U.K. in that vote, is its spokesman.

"Before I am unionist and before I am conservative, I am a democrat," said Duncan today in Barcelona in a press conference. "That's why I am here."

Duncan asked to meet the Spanish representative before the European Union ahead of coming to Barcelona. He didn't get any answer, he said.