Swiss voters were split down the middle on whether to curb immigration by European Union citizens, in a referendum seen as a crunch test of the country's ties with the 28-member bloc.
Fifty percent voted in favour and 50 percent against capping immigration, according to the latest projections by Swiss television station SRF.
Ten out of 26 Swiss cantons had voted in favour of the so-called initiate "stop mass immigration", projections showed.
The referendum, spearheaded by the right-wing Swiss People's Party (SVP), needs more than 50 percent to pass, as well as a majority of Switzerland's 26 cantons, which are the equivalent of US states.
A vote in favour, which comes 12 years after a free movement of people agreement with the EU came into force, could hurt the Swiss economy dependent on foreign professionals by increasing red tape and jeopardising bilateral accords with the bloc, according to Reuters news agency.
It would impose an absolute limit on the number of foreigners who can move to Switzerland each year.
The measure would bind the Swiss government to renegotiate within three years a deal with Brussels that since 2007 has given most EU citizens free access to the country's labour market.
It could also put Switzerland, which prides itself on a long humanitarian tradition, at odds with international accords on asylum.
To maintain its neutrality, Switzerland is not a member of the European Union, but has long-standing agreements with the EU and this vote is seen as a test of those ties.