Counting got under way Saturday in Ireland's historic referendum on same-sex marriage, with thousands of people, some of whom rushed home from living abroad to vote, gathering to hear the results.
The count started at 9:00 am (0800 GMT) in 43 constituencies across the country, with the smallest among them expected to start producing results from midday. The nationwide result is expected in the afternoon.
But "Yes" supporters were already optimistic of victory. A junior government minister with responsibility for equality, Aodhan O Riordain wrote on Twitter: "Key boxes opened. It's a yes. And a landslide across Dublin. And I'm so proud to be Irish today."
Another junior minister, Kevin Humphreys, said he was "happy to predict at this stage that it's going to be an overwhelmingly 'Yes' victory."
Legalising gay marriage would be a seismic change in the traditionally Catholic republic, where homosexuality was illegal until 1993 and abortion remains prohibited except where the mother's life is in danger.
Opinion polls forecast a comfortable victory for the "Yes" campaign. However, supporters have been warning for weeks of a large block of 'shy', largely rural and elderly "No" voters, who have not been as vocal in the campaign.
Around 3.2 million people were eligible to vote in Friday's referendum, and reports suggest there was a higher-than-expected turnout -- a testament to the passions the issue has inspired.
State broadcaster RTE said large numbers of young voters took part, with queues stretching outside some polling stations during the early morning and late evening peaks.
The issue drew intense interest on social media under the hashtag #MarRef, with some young Irish voters posting selfies of themselves returning from jobs in Britain and elsewhere to vote in favour of gay marriage.
In another sign of how much interest the referendum has attracted, the government announced that the 2,000-capacity grounds of Dublin Castle would be open to the public to hear the official result announcement.
If the move is approved and legislation is passed, Ireland would become the first country to make the change following a popular vote.
It would be the 19th country in the world to legalise gay marriage, and the 14th in Europe.
Across the border in Northern Ireland, gay marriage is banned even though it is legal in the rest of the United Kingdom.
All Ireland's main political parties, including the conservatives, supported amending the constitutional definition of marriage.
Gerry Adams, president of the socialist Sinn Fein opposition party, said Friday's referendum brought the issues of "inclusion and equality to the fore".
"Whatever the final outcome, the issue of equality for gay and lesbian citizens is a live political issue," he said.
The Yes Equality group, the driving force behind the "Yes" campaign, said the referendum would "inspire other countries to pursue and secure true equality".
Group co-director Brian Sheehan said that "regardless of the outcome of the campaign, Ireland can and will never go back to what it was".
"Yes" voters living around the world travelled home to have their say in the referendum.
A group of around 30 Irish people living in London arrived on the ferry into Dublin in high spirits, carrying banners and balloons and singing Elton John's hit "Are You Ready For Love".
"There are so many Irish immigrants who have left the country mainly for economic reasons in the past few years, but many of them intend to come back, and they want to play their part in shaping a better Ireland," Joey Kavanagh, who organised the "Get the Boat 2 Vote" group, told AFP.
Voters were asked whether or not to add an article to the Irish constitution saying: "Marriage may be contracted in accordance with law by two persons without distinction as to their sex."
The Catholic Church campaigned strongly for a "No" vote, insisting marriage can only involve a man and woman, and many older and rural voters agreed with the clergy.
"It's far too radical a step. I want to protect marriage and the stability of children," said Rachael Stanley, 60, voting in the south Dublin suburb of Milltown.
The majority of Irish people identify themselves as Catholic, although the Church's influence has waned amid growing secularisation and after a wave of child sex abuse scandals that badly discredited the hierarchy.