Rights activists are sounding the alarm over a referendum in EU-member Slovakia on Saturday designed to cement a constitutional ban on gay marriage, pointing to a rise in hate speech.
Amnesty International earlier this week accused the conservative circles that have pushed the referendum of "pandering to homophobic discrimination".
It added, in a statement, that any blanket ban on same-sex adoption would violate international human rights standards and the United Nations convention on discrimination against women.
"It's part of a resurgent wave of anti-gay movements in Europe" that also tried but failed to block gay marriage in France, said Guillaume Bonnet, director of the Paris-based All Out equality group.
Most Slovak voters have shown no interest in the referendum, while nearly half of those offering an opinion say they favour legalising same-sex unions.
However the opinion polls suggest that only a third of eligible voters will turn up at the ballot box on Saturday, well short of the 50 percent threshold required for the referendum to be valid.
Last month, Slovak SRo public radio pulled an episode of a regular religious programme that included hate speech against sexual minorities.
A transcript of the unaired sermon by a Greek Catholic priest slanders gays as "filth" and a "plague" that must be driven out of Slovakia.
Voting in the gay marriage referendum will start Saturday at 0600 GMT and finish at 2100 GMT. There are nearly 5,000 polling stations to serve around 4.4 million eligible voters. The results are expected late Saturday.
The vote will also focus on adoption rights for same-sex couples and whether sex education and lessons on euthanasia should be made compulsory at school.
One of several controversial videos posted on YouTube by gay marriage opponents shows an orphan asking "Where's the mother?" when he discovers that his adoptive parents are both male.
Opponents of gay marriage deny having a homophobic agenda.
"The referendum isn't against same-sex couples, it's for children," Anton Chromik, spokesman for the Alliance For Family (AZR) that spearheaded the referendum, told AFP.
"Same-sex couples have the right to privacy, to freedom," he said, but "children deserve both a mother and a father".
"The European Parliament and some EU member states have passed laws that undermine the unique nature of marriage, families and children's rights. We're worried about parents losing the freedom to raise their kids according to their beliefs."
EU rules allow each of the bloc's 28 members to make their own decisions on issues like marriage and adoption.
A 2012 opinion poll in Slovakia showed that 47 percent of respondents supported civil unions for gays. Thirty-eight percent were opposed in the country of 5.4 million people, where 69 percent identified themselves as Roman Catholic in a 2011 census.
The Slovak ban on gay marriage contrasts sharply with its legalisation in more than a dozen countries, including Argentina, France and the United States.
Leftist Prime Minister Robert Fico sought to sway conservative voters in his failed presidential bid in 2014 by amending the constitution to define marriage as a union between man and woman, effectively banning same-sex marriage.
To ensure the ban would stick, the AZR went ahead and gathered the 400,000 signatures needed for the referendum.
For Bratislava art gallery owner Andrea Pallang, 40, who has been living with her girlfriend for eight years, the ban hits very close to home.
"I feel discriminated against in tax, social and healthcare policies," Pallang told AFP, adding that "it's as if we don't exist."
But the AZR has convinced 27-year-old tourist agent Eva Lajchova. The Bratislava resident says she backs the ban "because I care about the future of Slovakia and my future children."
Marian Lesko, an analyst with the Bratislava-based Trend business weekly, explains the larger factors behind the prospect that the ban will remain intact for some time.
"Compared to neighbouring countries, Slovakia is quite conservative in respect to cultural-ethical issues due to strong religious beliefs, the country's isolation during the communist-era and a fear of diversity," he told AFP.