The rightwing Swiss People's Party has confirmed its opposition to the extension and continuation of a labour treaty between Switzerland the European Union.
Delegates on Saturday overwhelmingly came out against a parliamentary decision which will go to a nationwide vote next February. They also rejected the option of a boycott of the ballot.
The youth wing of the People's Party and small far-right groups collected enough signatures for a referendum.
They argued it was undemocratic to lump into one bill the continuation of the labour treaty with 25 EU members and a planned extension to the newest members Romania and Bulgaria.
The People's Party leadership initially said it would not support its youth chapter, but later changed its stance.
The government, the other main political parties, as well as the business community all backed the treaty.
Switzerland is not a member of the EU, but it has concluded 20 major bilateral agreements, including a free trade accord and a labour treaty since 1972.