Swiss voters will take up an unprecedented proposal to limit Switzerland’s population, part of a longtime push by right-wing leaders to cap the number of foreigners who migrate to the rich and economically vibrant Alpine country.

A national vote on whether to cap Switzerland’s population at 10 million in coming decades culminates with in-person balloting on Sunday. Swiss democracy gives voters a direct say in policymaking through referendums typically held four times a year.

The proposal is backed by the populist Swiss People’s Party, which has the most seats in parliament and has for years thrived off and fomented an isolationist streak in Switzerland.

Recent polling from the gfs.bern agency suggested that it could be a close contest.

A self-inflicted wound, or salvation for Swiss-ness?