LEADING members of the 'Yes' campaign were optimistic last night that a high turnout in the marriage equality referendum means victory is secured.
Dublin emerged as the epicentre for the 'Yes' campaign, with turnout reported as high as 70pc in locations such as Donnybrook.
Voters flocked to polling stations from early morning to have their say in the historic vote.
Both sides were reluctant to claim victory, but campaigners for a 'Yes' vote were quietly confident that the high turnout - especially among young voters and in urban areas - gave them a good advantage before ballots were counted.
Turnout for the world's first vote on legalising same-sex marriage was expected to reach around 60pc in cities and about 50pc in rural areas before voting closed.
Traditionally, referendum turnouts are low - such as the Seanad abolition vote which saw fewer than 40pc of the electorate take to the ballot box.
However, there were reports of queues outside polling stations from 7am yesterday, which campaigners in both camps said was evidence of the huge public engagement on the divisive issue. A higher-than-expected youth vote will impact on the final count as thousands of young people who have never voted before made their way to polling stations.
In total, 66,000 people were added to the supplementary register to vote in the referendum.
Social media campaigns and an unprecedented number of people returning home to Ireland to vote in the referendum mean the final decision will be carried by a significant mandate.
Fine Gael director of election, Agriculture Minister Simon Coveney, said he was taking nothing for granted but was heartened by the high turnout.
"My sense is that a good urban turnout has to be positive for the 'Yes' side and reports of lots of young people voting is very positive as well. We are not getting carried away, but we are very hopeful given the activity we have seen today," Mr Coveney told the Herald.
"I am hoping we get a clear result and we are not scraping over the line, but I am not going to be so presumptuous to say it is a success.
"If this was lost there will be many thousands of people and families devastated on a personal level. People think their country is doing something very positive today. It's almost like we are letting go of something negative in terms of prejudice and the way people look at the gay community.
"People are making a decision to let that go and want a different relationship with that community in the future and I think that's really powerful.
Senator Ronan Mullen, who advocated for a 'No' vote, said the high turnout was a "real tribute to the public's social concern".
He conceded that a strong youth vote is more of an advantage to the 'Yes' side, but dismissed suggestions that there was less of a 'No' vote in urban areas.
"There are lots of people in urban areas who have been soul-searching in recent weeks and were undecided on how to vote," said Mr Mullen.
"This was not necessarily about a liberal conservative divide."
Emergency ballot boxes were on stand-by in Carlow and Kilkenny yesterday as huge numbers of voters descended on polling stations to cast their votes in the by-election and two referenda.
Polling station turnouts were far in excess of what was expected, with some centres seeing more than 50pc of the electorate voting around teatime and ahead of the traditional rush of evening voters.
Returning officer Marian Kilbride said she was getting panicked calls from polling stations where ballot boxes were overflowing.
"The boxes were filling up quickly and people keep panicking. We have standby boxes but we are telling them to get a ruler and push them in," said Ms Kilbride.
In Dublin, there was criticism after a polling station turned away up to five voters with disabilities.
Fianna Fail councillor Cormac Devlin said the issue arose at St Kevin's National School in Sallynoggin.
"I am shocked that a situation can arise in 2015 that someone is unable to access their local polling station," Mr Devlin said.