Swiss voters are heading to the polls to decide on a controversial initiative sought by a right-wing, nationalist party that could lead to automatic expulsions of foreigners who commit even low-level crimes.

The referendum Sunday follows repeated efforts in recent years to tighten measures against foreigners, but the Swiss People's Party says they have not gone far enough.

Polls suggest a close race in the balloting that could lead to automatic expulsions for severe crimes like rape or murder, but also in cases of low-level crimes like speeding or insulting police if they are committed twice within a ten-year span.

Critics say the measure would stigmatize foreigners unfairly but the right-wing party insists it is the people's will.