STOCKHOLM, Sweden -- In a shopping mall in Haninge, a blue-collar suburb south of the capital, campaign volunteers worked the noonday crowd Thursday, handing out pamphlets and bright blue buttons emblazoned with a single word: "Yes."
"The European train is leaving now, and Sweden has a ticket," read one of the fliers pushed into the hands of passersby. "Don't throw it away."
Across the mall, beside a bakery, members of a rival group distributed lapel pins with the slogan "No to the EU."
Among the piles of booklets and bulletins stacked on a table was one illustrated with a cartoon, showing a leering European whale preparing to swallow a tiny Swedish fish.
In towns and villages across the country, voters will cast ballots today in a national referendum on whether Sweden should join the European Union in pursuing common economic and political ambitions.
Public opinion polls suggest that Sweden's 6.5 million voters are having a hard time making up their minds. While voter surveys show those who are opposed to membership slightly ahead of those in favor, experts say that the outcome is too close to predict. At least one in four voters acknowledge that they do not know which way they will cast their ballot.
Annette Hasslund, a hospital worker in Haninge, was among a group of about 100 people at the mall who listened as Margot Wallstrom, the culture minister, campaigned on behalf of the referendum.
"I don't want Sweden to be left behind, but I also worry what will happen to our clean air and clean water," said Ms. Hasslund, reciting a common fear that membership will force Sweden to compromise its strict environmental standards for looser European rules. "I don't think we need Europe that badly."
Political leaders in Sweden have promised that they will abide by the outcome of today's national ballot. Legally, it is Sweden's Parliament that will finally decide whether the country joins the European Union.
Finland and Austria decided to join this year, and membership would rise from 12 to 16 on Jan. 1 if there is also agreement from Sweden and Norway, which has scheduled a referendum for Nov. 28.
Here in Sweden, the ballot comes during a period of self-doubt, ** aggravated by an economic collapse that not only has driven record numbers of people out of work but has also forced cutbacks in welfare benefits that had been a source of Swedish national pride.
Even now, Sweden is hobbled by one of the highest national debts among industrialized nations, 83 percent of gross domestic product, as the government of Prime Minister Ingvar Carlsson tries to cut spending, increase revenue and restore some stability to financial markets.