For a full-time worker, the proposed minimum wage would amount to nearly two-thirds of Switzerland’s median salary in 2012, according to official numbers. Of the 339,000 people the federal statistics office estimates currently earn below the median salary, two out of three are women, most of them working in retail, hotels or personal services.

Recent surveys have suggested waning support for the measure, but the government was caught off guard in February when citizens unexpectedly voted to restrict the number of European Union citizens allowed to live and work in the country. Under Switzerland’s system of direct democracy, anyone can propose an issue, and if it wins enough support, it is put to citizens for a vote.

Switzerland remains one of the most business-friendly countries in Europe, but the series of referendums focusing on economic issues in the last two years has rattled many executives. Some of the country’s largest companies, which include Nestlé and Swatch, say they fear that introducing a minimum wage could damage competitiveness.

Two-thirds of Swiss jobs are in small and midsize businesses. Owners of hotels, restaurants and retailers, especially in cities near the borders, are fearful that the proposal would force them to cut largely untrained cleaning and kitchen staff members, because they would otherwise be required to pay them salaries equivalent to that of receptionists or waiters with two to three years’ vocational training.

They also argue that a minimum wage would have the opposite effect of that desired by the unions, by forcing more people into part-time jobs that would increase the country’s unemployment rate, which stood at 3.2 percent in April, according to government figures.

“The initiative would be a boomerang for Switzerland,” said Marcel Schweizer, president of Gewerbeverband Basel-Stadt, a trade association in Basel representing small and midsize businesses. “Many branches would be forced to cut jobs that would become too expensive. The hardest hit would be poorly qualified workers.”

The Association of Swiss Cleaning Companies, Allpura, issued a sharply worded statement in which it opposed the wage initiative because it “destroys jobs and weakens Switzerland’s competitiveness.” It said cleaners earn 18.50 to 26.50 francs an hour.