By Imogen Foulkes
BBC News, Bern
The SVP campaign has provoked accusations of racism
The Swiss are poised to vote on whether to revive secret ballots to decide on citizenship - an issue that has stirred passions on both sides.
Switzerland's Supreme Court outlawed the secret ballots five years ago, ruling that they were discriminatory. But many Swiss say not allowing voters to have the final say violates Switzerland's system of direct democracy.
Switzerland already has some of the toughest naturalisation laws in the world.
Candidates for citizenship must have lived in the country for at least 12 years - they must prove that they can speak the local language, and that they understand Swiss laws and culture.
What is more, being born in Switzerland does not bring an automatic right to citizenship.
In Switzerland, people wanting to be Swiss must apply through their local community. In many towns and villages, the final hurdle to citizenship is often the approval of local residents at a town hall meeting, or, in the past, by secret ballot.
Two ethnic Turkish men, Elias Ego and Manuel Dogdu, have long experience of this process.
They have lived all their lives in the central Swiss town of Schwyz, but they have Turkish nationality. Schwyz, with a population of 14,000, was one of the towns which used secret ballots to approve new citizens.
"They distributed brochures with our pictures to all the voters," remembers Elias. "There was a little CV with information about us, and our nationality."
"We had passed all the language tests with flying colours," adds Manuel. "The authorities recommended us for citizenship."
Manuel and Elias, together with their parents, brothers and sisters, had hoped the ballot would be a formality. Instead it turned out to be a humiliating public rejection.
"We've been rejected four times now," says Manuel.
"I'm very, very disappointed. I can't understand why I can't be Swiss - Switzerland is my home, I've lived here all my life."
Manuel's fate is in the hands of the people of Schwyz
"We were rejected three times," adds Elias, who is now 20.
"I remember, every time, I had to go to school the next day, and everybody knew exactly what had happened. Some people pointed and laughed. It was very tough."
The cases of Elias and Manuel are not unique. In towns which used the ballot system, candidates from Turkey, the former Yugoslavia and Africa were regularly rejected, despite having satisfied all the requirements for naturalisation, while those from Western Europe were approved.
Five years ago, the Swiss Supreme Court outlawed secret ballots, ruling that they could be discriminatory. At the same time, the court ruled that those turned down for citizenship had the right to be given reasons for their rejection, and the right to appeal against the decision.
The ruling brought a storm of protest. Switzerland's tradition of direct democracy generally means the people, the voters, have the final say. Many see the Supreme Court's action as an attack on the very foundations of the Swiss democratic system.
"I cannot accept that judges have the right to decide who gets to be a citizen," says Luzi Stamm, member of parliament for the right-wing Swiss People's Party (SVP).
"Citizenship is a political question. The Swiss population, Swiss society should decide - not lawyers and judges."
The SVP, now the largest party in Switzerland's parliament, has forced the issue to a nationwide referendum. On Sunday voters will decide whether to revive secret ballots and remove the right of appeal, thus giving the final say on naturalisation back to the Swiss people.
The campaign has been heated. Normally tranquil Swiss political talk shows have descended into bitter shouting matches.
The SVP's campaign poster, showing black and brown hands grabbing at Swiss passports, has led many to suspect that the real issue is not who decides on citizenship, but how best to keep certain groups out of Switzerland.
In fact, many in the SVP make no secret of this. For member of parliament Peter Foehn, discrimination is not a problem, as long as people have the right to vote.
"If our people, our voters, have the feeling we've had enough from former Yugoslavia, or wherever, the rest will just have to accept it. The people's decision is final."
But for Switzerland's large foreign community - currently 21% of the total population - it may be hard to accept. Many, like Elias and Manuel, know no other home.
"I feel Swiss, I was born here, all my friends are here. For me, this is like my country, my identity," says Elias.
Elias finally got his Swiss citizenship at the fourth attempt, after 10 years of trying, once secret ballots had been outlawed. If they were still being used, he believes he would still be waiting - like Manuel.
"I'm hoping my fifth application will be approved in the spring," Manuel says. "But if they say yes to bringing back ballots, I'll have to go through all that again."
And for Elias, the whole experience has made him question what Switzerland really means by direct democracy.
"How can they do it?" he asks. "They just look at our pictures, and our nationality, and for them that's enough to decide our future? It's not fair. We're living in a democracy, something like that shouldn't be possible."