Voters in Switzerland on Sunday will decide the fate of a same-sex marriage bill approved by lawmakers.

While gay and lesbian couples have been able to enter a civil partnership since 2007, lawmakers extended civil marriage to same-sex couples late last year. Opponents of the proposed law forced a referendum on the issue, Reuters reported.

The campaign to repeal the bill has gained some steam, with the latest poll numbers showing a 6 percent increase in opposition from a month earlier (29 percent to 35).

The amended law would also allow same-sex couples to adopt children unrelated to them.

Gay couples have been allowed to adopt their partner's children since 2018.

Switzerland is one of the last Western European countries without marriage equality.