Catherine Murphy, co-leader of the small Social Democrats party, said the polls strongly indicate that "voters have taken on board the clear message that the constitutional ban harms women" and must be removed from the Constitution.

If the exit poll numbers hold up, the victory will be of a larger magnitude than "yes" activists had believed possible. It would then fall to Parliament to establish new laws governing abortions.

The government proposes that the law be changed to allow unrestricted access to abortions up to 12 weeks of pregnancy. Later abortions would also be allowed in special circumstances.

Ireland's referendum represented a battle for the very soul of a traditionally conservative nation that has seen a wave of liberalization in recent years.

The traditionally Catholic country has some of the most restrictive abortion laws in the European Union, with Malta — where abortion is banned under all circumstances — the only member of the 28-country bloc with tighter legislation.

Abortion is currently permitted in Ireland only if a woman’s life is in danger, which includes the risk of suicide. It is not permitted in cases of rape, incest or fetal abnormalities.

More than 3.2 million people registered to vote in the referendum.

Ireland is one of the few E.U. countries that does not allow those abroad to vote by mail or at embassies, so many expatriates traveled to cast their ballots and shared their journeys on social media under the hashtag #hometovote.

Thousands of dollars were raised on Facebook overnight for people who realized that they could make it back to Ireland to vote but could not afford the last-minute flights.

Members of the Abroad for Yes group wired donations to people no longer living in Ireland.

Becky Breakey, who lives in the Hungarian city of Budapest, was able to travel after she posted that it would cost her 555 euros ($644) to return home. Aisling Cotter said she reached her target to get back from London after just eight minutes, while others were given enough money to fly from as far away as Montreal.

The referendum follows an emotive and often acrimonious campaign.

Irish Prime Minister Leo Varadkar, who is in favor of change, has warned that the referendum is a “once-in-a-generation” opportunity.

A poll published by the Irish Times/Ipsos MRBI on May 17 found that 44 percent of respondents intended to vote “yes” to repealing the Eighth Amendment, compared with 32 percent who said they would vote “no.” However, support for the anti-abortion campaign has grown in recent weeks, and 24 percent of respondents said they remained undecided or were not planning to vote.

Saphora Smith reported from London.