Two polls on behalf of national broadcaster RTE and the Irish Times suggest a landslide victory for those campaigning to liberalise the law and open up access to abortion.
The RTE/Behaviour and Attitudes poll showed 69.4% are in favour, while the Irish Times/Ipsos MRBI poll put the figure just slightly lower at 68%.
The Irish Times poll surveyed 4,000 voters at 160 polling stations in every constituency in Ireland, while the RTE surveyed 3,800 people at 175 stations across the country.
The official result is due on Saturday – with the count beginning at 9am – and if similar to the exit poll it will be a historic victory.
Sky’s senior Ireland correspondent David Blevins said it was a wider margin than many people in the Catholic country had expected.
Turnout could be higher than for the vote on same-sex marriage three years ago, said Irish national broadcaster RTE.
Prime minister Leo Varadkar, who supported the campaign to liberalise Ireland’s abortion laws, said: “It’s looking like we will make history tomorrow.”
UK Minister for Women and Equalities Penny Mordaunt said it was a “historic & great day for Ireland, & a hopeful one for Northern Ireland”.
She tweeted: “That hope must be met. #HomeToVote stories are a powerful and moving testimony as to why this had to happen and that understanding & empathy exists between generations. #trustwomen”.
If the victory is officially confirmed, Ireland’s government says it is committed to introducing unrestricted access to abortion for women up to 12 weeks pregnant.
After that, abortions will only be allowed until the 24th week of pregnancy if there is a risk to a woman’s life, or a risk of serious harm to the physical or mental health of a woman.
Under the current law, an unborn child has the same right to life as the mother.
The maximum penalty for accessing an illegal abortion is 14 years in prison.
There have been six referendums on the matter of abortion in the past 35 years in Ireland, and the issue has long divided the country.
Many Irish women seeking an abortion are forced to travel abroad, often to the UK.
‘Home to vote’ campaigns had gained momentum in recent weeks, bringing hundreds of young people back to exercise their democratic right.
Others made the journey to “Save the Eighth” – the 1983 amendment to the constitution that equates the life of the unborn child with the life of the mother.
The effective prohibition on abortion in Ireland was partially lifted in 2013 for cases when a mother’s life was in danger.
The referendum on the issue rose towards the top of the political agenda after the death of Savita Halappanavar in 2012.
The 31-year-old was miscarrying her first baby and was refused a termination at a hospital in Galway. She died of blood poisoning.
However, campaign group Save The 8th says politicians are “effectively seeking a licence to kill pre-born babies, and to introduce an abortion model that is in many ways even more extreme than the British regime”.
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It says the current law protects the mother as much as the baby, and denies the rules have ever stopped doctors giving a woman life-saving treatment.
Some also fear that prenatal screening teamed with legal abortion could lead to the eradication of people with Down’s syndrome if the Irish constitution is changed.