The Swiss are split on whether to extend a bilateral treaty on the free movement of people to the new members of the European Union.
The latest poll by the Bern-based Gfs Institute, carried out on behalf of the Swiss Broadcasting Corporation – swissinfo’s parent company - found 43 per cent in favour and 40 per cent against the accord.
The survey, released on Friday, found that 17 per cent of voters were still undecided. The vote is set for September 25.
The poll found voters clearly divided along party lines with an overwhelming majority (87 per cent) of followers of the rightwing Swiss People’s Party against extending the treaty to the ten new - and mostly eastern European - EU members.
This is despite about a third of People’s Party parliamentarians announcing recently that they would not follow the party, but would support the accord.
A majority of followers of the other three parties represented in government said they would say "yes" in September: 74 per cent of Social Democrats (centre-left), 63 per cent of Radicals (centre-right) and 56 per cent of Christian Democrats (centre-right).
The results of the survey also revealed cultural divisions, with more French speakers in favour (47 per cent) than German-speaking Swiss (41 per cent). Italian speakers are the most sceptical, with only 40 per cent in favour and 47 per cent against.
The poll also revealed that voters who live in urban areas and who have a good education and salary generally approved of extending the treaty, while those living in rural areas were more likely to be opposed.
Voter turnout is expected to be high on September 25. On average, only about 40 per cent of the electorate bother to cast their ballots in referendums, but 55 per cent of those surveyed said they would definitely vote, while a further 23 per cent said they were undecided.
The Gfs Institute reasoned that the increased interest was due to the fact that the campaign began immediately after the last nationwide vote in June on a related subject - the Schengen/Dublin accords on closer ties on security and asylum issues with the EU.
Opening Switzerland's labour market to the EU's new members was also part of the debate ahead of the Schengen/Dublin vote.
The government and business leaders argue that the Swiss economy will benefit from extending the treaty and there could be problems with the EU if voters reject the accord.
This view is shared by 52 per cent of people surveyed, while 46 per cent believe a "no" could jeopardise Switzerland's other bilateral treaties with the EU.
But 70 per cent also fear that opening up the Swiss labour market will push down Swiss salary levels and 60 per cent think it will lead to mass immigration from eastern Europe.
43% said they were in favour of extending the treaty to new EU members.
40% are opposed.
17% are undecided.
The Swiss go to the polls on September 25 to decide whether to extend a free movement of people treaty to the new members of the EU.
The ten countries which joined the EU on May 1, 2004 are: Lithuania, Latvia, Estonia, Poland, Hungary, Slovakia, the Czech Republic, Slovenia, Cyprus and Malta.
On June 5, 54.6% of Swiss voters approved a decision to join the EU's treaties on Schengen and Dublin.