Female opposition to joining the EU is turning out to be one of the crucial factors in the vote. As in other Nordic countries, Norwegian women play a bigger role in political life than anywhere else in Europe.
The spearhead of the ''Yes'' lobby is Gro Harlem Brundtland, the Labour Prime Minister, who is one of Norway's most experienced and popular politicians. Known simply as Gro, she is well enough liked for 59 per cent of voters to want her to continue as Prime Minister even if the referendum produces a ''No'' result.
Mrs Brundtland hopes Norwegians will join the EU if only because they have seen their Nordic neighbours, Sweden and Finland, vote ''Yes'' in the past two months. ''Norwegians are well aware that Sweden is our closest and most important neighbour. It is our main trading partner, and that has implications for Norwegian jobs,'' she says.
The leader of the ''No'' campaign is Anne Enger Lahnstein, head of the opposition Centre Party, which speaks for Norway's heavily protected agricultural interests, but is also critical of what it portrays as excessive bureaucracy and centralisation of power in the EU.
''Our resistance to the EU is based on the experiences of generations. We do not want to be ruled from abroad,'' Mrs Lahnstein told a rally of 20,000 people in Oslo last week.
Many Norwegians think the EU fails to match their own high standards; Norway prides itself on having constructed a system of sexual equality in legal, economic and social matters.
The male dominance of the three main EU institutions - the Council of Ministers, Commission and Parliament - may not be quite as overwhelming as it once was. For example, the new leader of the Socialist group in the Parliament is Pauline Green, a Briton, and the recently appointed Commission under Jacques Santer has more female members than ever, including the former French prime minister, Edith Cresson.
Still, it is common to hear Norwegians mock the EU as a ''male playground'', dominated by such turn-offs as Jacques Delors, Helmut Kohl and thousands of men in suits.
But the deeper reason for Norwegian women's hostility to the EU appears to lie in the transformation of the country's employment structure over the past 20 years. In 1972, when Norway narrowly rejected joining the European Community in a referendum, women cast their votes in almost exactly the same proportions as men.
This time, says Tor Bjorklund, a political scientist at Oslo University, ''the strongest opposition is undoubtedly that found among women in the public sector''.
Norway's public sector has expanded greatly since the early Seventies, and women working in it now make up more than 20 per cent of the workforce. While they will not vote as one bloc, surveys show that support for EU membership runs at only 24 per cent among women in the public sector - the lowest of any employment category. The reason is that Norwegian women expect EU membership to force cuts in government spending and jobs; Norway's public sector is much larger than the EU average, and women depend on it, especially if they have families. (It offers a generous support system with schemes for maternity leave, guaranteed employment and facilities for children.)
Norwegian women who have taken jobs in the past 20 years - and about 75 per cent of all adult women now work compared with 50 per cent in 1972 - fear that these benefits will be undermined by EU membership.
They perceive the EU as an institution so committed to the philosophy of the free market it will attack the Norwegian tradition of the interventionist, job-protecting state.
Similar concerns were expressed during Sweden's referendum, but in the end the ''Yes'' campaign squeaked through. In Norway, there are so many other factors working in favour of a ''No'' vote - from the defence of national sovereignty to protection of the environment to a feeling that, unlike in Sweden, the welfare state is not in particular need of reform - that pro-EU campaigners face a much harder task.
If they win, the EU can expect Norway to press for women to have a much higher profile in European affairs.