Unlike in many other countries, a person does not automatically become a Swiss citizen if they are born in the country. If neither their parents nor grandparents were Swiss, that could mean they are the third generation of a family living in the country without citizenship.
The government is backing a change to the constitution that would give young third generation immigrants who were born and schooled in Switzerland access to the ‘facilitated naturalization’ process, an easier and less long-winded version of the usual citizenship procedure.
To apply for facilitated naturalization they must have been born in Switzerland, have completed at least five years of schooling here and have a permanent residence permit.
Their grandparents and parents must also meet certain conditions related to residency and schooling.
Applicants cannot be over 25 years of age – a proviso added in parliament over fears people could shirk their military service obligations by only applying for citizenship after that age.
According to a recent study Switzerland has 24,650 third generation immigrants aged 9-25 who meet these criteria.
An estimated 60 percent of them are Italian, according to a government study.
But that hasn’t stopped a committee campaigning against the proposed change to the law from using a controversial poster showing a woman wearing a niqab or burqa above the tagline ‘Uncontrolled naturalization? No to facilitated naturalization”.
Critics of the campaign image distributed across the country ahead of Sunday's referendum say the poster is really just a brazen appeal to those worried about more Muslims becoming Swiss.
"That is exactly what they are trying to (do)", said Pius Walker, who heads the Zurich-based advertising agency Walker AG.
"It is a very, very frightening thing that is going on here."
The committee is backed by many members of Switzerland’s right-wing, anti-immigration Swiss People’s Party (SVP).
In campaigning against the measure, SVP has made clear that Italians were not its primary concern.
"In one or two generations, who will these third generation foreigners be?" SVP lawmaker Jean-Luc Addor wrote in an opinion piece on the party's website.
"They will be born of the Arab Spring, they will be from sub-Saharan Africa, the Horn of Africa, Syria or Afghanistan," he warned.
SVP members are no strangers to campaigns denounced as discriminatory, notably a successful 2009 initiative to outlaw the construction of new mosque minarets.
Campaigns demonizing Muslims are expected from the SVP, but they are not "deemed acceptable" by the Swiss political mainstream, said Sophie Guignard of the Institute of Political Science at the University of Bern.
For most politicians and journalists, the burqa poster amounts to "a violent attack against Muslims," Guignard told AFP.
But that does not mean it won't work.
The latest polls from the gfs.bern institute show 66 percent of people support easier citizenship for third-generation immigrants, with 31 percent against and three percent undecided.
Polls from the news company Tamedia have it closer, with 55 percent in favour and 44 percent against.
The "No" side has however gained about 10 points since polling opened.
And an upset can't be ruled out, especially with the touchstone issue of Swiss identity and Islam at the centre of the debate.
Facilitated naturalization is already available to foreign spouses of Swiss citizens who meet certain conditions.
It is generally a much shorter and simpler process than regular naturalization, which is decided by the cantonal and communal authorities of the area in which the applicant lives.
The Swiss people are voting on two other issues on Sunday, a proposed tax reform for businesses and a project that would guarantee funding for roads and traffic infrastructure.