– In a warehouse in Barcelona, more than a thousand volunteers worked shifts through the summer bombarding Catalan voters with phone calls to persuade them to abandon Spain.

From the call center, the volunteer army has made more than 300,000 calls and had conversations with more than 56,000 people leading up to Sunday’s regional election.

Working with advisers who helped Barack Obama’s 2008 presidential run, they asked voters how they would spend an $18 billion annual windfall from independence: Did they want to help the poor? Upgrade the region’s infrastructure? Raise pensions?

But secession will bring no such windfall — at least not according to the pro-independence officials in charge of the regional administration.

An independent Catalonia would have had a modest surplus this year, according to estimates by the Catalan Economic Department. Regional President Artur Mas’ election manifesto relies on optimistic fiscal benefits. Neither includes the untold costs of potentially getting kicked out of the euro, which Spain’s central bank governor Luis Maria Linde warned of this week.

“It’s all a massive propaganda effort to bring people who don’t have a strong independence sentiment to embrace independence for economic reasons,” said Josep Borrell, the former president of the European Parliament who has been touring his home region trying to paint a different picture of independence.

Independence on the line

After a five-year campaign and centuries of resentment, Catalans are voting for the first time this weekend in a legally sanctioned ballot on which the central question is whether to remain part of Spain.

Voters in the economically powerful region of northeastern Spain are being presented with two choices: parties promising efforts to make Catalonia independent, and parties that want Catalonia to keep its special identity but don’t want it to break away. Polls show the independence parties headed for a slim win.

An independent Catalonia would be automatically excluded from the European Union and the single currency unless European officials would bend the rules to accommodate them. Catalan banks could still borrow from the European Central Bank if they were outside the euro. Or they’d run out of cash and be forced to freeze deposits.

“People don’t have a clear sense of what the consequences of the vote really are,” said Felix Ovejero, a sociology professor at Barcelona University, who supports Catalonia remaining part of Spain.

The pro-independence canvassing operation was set up by the Catalan National Assembly, or ANC, and Omnium Cultural, the civic organizations that have brought hundreds of thousands of demonstrators onto the streets of Barcelona each year since the Constitutional Court revoked part of the region’s autonomy in 2010.

If the pro-independence movement wins, it would be near a majority in the regional assembly, a threshold that could trigger an 18-month race to build the structures of a new state in defiance of Spain.

The separatist groups ran a similar canvassing operation to mobilize voters before the informal referendum held in November last year. More than 2 million people voted, even though Spain’s constitutional court ruled the ballot illegal.

That ground campaign is backed up by the news shows on the regional government television channel TV3, the most popular among Catalans.

Skewed TV coverage

When Obama said last week that he favored a “strong and unified Spain,” TV3 gave the comments seven seconds of airtime. Spanish Prime Minister Mariano Rajoy got 15 seconds while Mas’ response lasted for 52 seconds.

Catalans say that they themselves are the victims of bias. Spain’s national media are skewed against the independence movement, according to critics. About 96 percent of guests discussing Catalan politics on national channels oppose independence, according to a study presented by the two civic groups last week.

“I’ve heard complaints about the plurality of the Catalan media,” said Jordi Sanchez, the head of the ANC. “But the numbers show that it’s more a problem for the media in Madrid.”

As Borrell, who led the Socialist opposition for a year in the late 1990s, toured Catalonia this month, he found that the regional parties have had more success getting their message across than those in the national capital.

“Messages such as ‘Spain robs us’ have created a breeding ground for emotions and have gone unanswered,” he said. “We’ve collectively abandoned the civic and media space to the pro-independence camp.” He’s hoping it’s not too late to claim it back.