GENEVA (AP) — Voters in Switzerland are casting final ballots in a referendum on whether same-sex couples can be allowed to marry.

In-person voting was taking place Sunday morning across the rich Alpine country to cap the latest of Switzerland's regular referendums that give the public a direct say in policymaking. Most ballots are cast by mail, and polls close at noon local time (1000 GMT).

Switzerland's parliament and the executive Federal Council support the “Marriage for All” measure, for which the most recent voter polls showed solid backing. Switzerland has authorized same-sex civil partnerships since 2007.

Supporters say passage would put same-sex partners on equal legal footing with heterosexual couples such as by allowing them to adopt children together and facilitating citizenship for same-sex spouses. It would also permit lesbian couples to utilize regulated sperm donation.

Opponents believe that replacing civil partnerships with full marriage rights would undermine families based on a union between one man and one woman.

The campaign has been rife with allegations of unfair tactics, with the opposing sides decrying the ripping down of posters, LGBT hotlines getting flooded with complaints, hostile emails and shouted insults against campaigners, and efforts to silence opposing views.

Switzerland, which has a population of 8.5 million and international prestige due to Geneva’s role as the home of the United Nations in Europe, is traditionally conservative and only extended the right to vote to all its women in 1990.

Most countries in Western Europe already recognize same-sex marriage, while most of those in central and Eastern Europe don't allow wedlock involving two men or two women.

Even if the Swiss referendum passes, supporters say it would be months before same-sex couples could get married — mainly because of administrative and legislative procedures.

Another issue on Sunday’s ballot is a measure spearheaded by left-wing groups to raise taxes on returns from investments and capital such as dividends or income from rental properties in Switzerland as a way to ensure better redistribution and fairer taxation.

Polls suggest that referendum is unlikely to pass in a country known for its vibrant financial sector and relatively low taxes, and as a haven for many of the world’s richest people.