Dublin - Irish voters backed same-sex marriage by a landslide in a referendum marking a dramatic social shift in the traditionally Catholic country, government ministers and opponents of the bill said on Saturday.
Final results were not expected until later in the day, but ministers predicted Ireland had become the first country to adopt same-sex marriage via a popular vote by a margin of around two-to-one, just two decades after it decriminalised homosexuality.
"This has really touched a nerve in Ireland," Equality Minister Aodhan O'Riordain said at the main count centre in Dublin. "It's a very strong message to every LGBT (lesbian, gay, bisexual, and transgender) young person in Ireland and every LGBT young person in the world."
Health Minister Leo Varadkar, who revealed he was gay in a radio interview in January, said the referendum resembled a "social revolution."
The proposal was backed by all political parties, championed by big employers and endorsed by celebrities, all hoping it would mark a transformation in a country that was long regarded as one of the most socially conservative in Western Europe.
Only a third of the country backed the decriminalisation of gay sex for men over 17 in 1993, according to a poll at the time. A supreme court judge in 1983 said homosexuality was "morally wrong" and contributed to depression and suicide.
"This is a big placard from the people of Ireland to the rest of the world saying this is the way forward," said David Norris, who began a campaign for gay rights in the late 1970s.
The Catholic Church, whose dominance of Irish politics collapsed in the wake of a series of sex scandals in the early 1990s, still teaches that homosexual activity is a sin. But it limited its 'No' campaigning to sermons to its remaining flock, a marked contrast with active public opposition to similar moves in France and elsewhere.
Instead, lay groups led the opposition by raising concerns over parenthood and surrogacy rights for gay couples. Many believe the recognition of the legal rights of same-sex couples in 2009 is sufficient.
One of the main opponents of the bill conceded minutes after the first boxes were opened.
"Everyone seems to be predicting a 'yes' ... and that seems to be the case at the moment. It's disappointing," said John Murray from Catholic think tank the Iona Institute.
State broadcaster RTE said up to 80% of voters backed the 'Yes' campaign in some working-classing areas of Dublin. The vote was much closer in many rural areas, but the vast majority of constituencies appeared likely to back 'Yes', RTE said.
At the main count centre, 'Yes' supporters embraced, cried and waved rainbow flags as the high approval rate became clear.