The Republic of Ireland is preparing to hold the world’s first popular vote on same-sex marriage on Friday as polls suggest the country will come out in favor of the new law.

It will be the first country to hold a national referendum on whether to enshrine legal protection of marriage equality in the nation’s constitution.

A poll conducted by Irish market research agency IPSOS MRBI last weekend showed 58 percent of those surveyed planned to vote in favor of gay marriage. Some 25 percent intended to vote against it, while 17 percent were undecided.

Whereas other countries have simply changed the law to enshrine marriage equality, Ireland’s written constitution can only be amended by a national referendum.

The constitution does not define marriage as solely a male-female affair. However, had Ireland introduced protection for gay marriage without a popular vote it could have left the government open to a legal challenge in Ireland’s Supreme Court.

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This could have sparked drawn-out legal battles, with the Irish government being forced to hold a referendum in the end. Observers say the coalition government opted for a popular vote to avoid this scenario.

Irish Prime Minister Enda Kenny made a final plea for a “Yes” vote on Wednesday.

Speaking on Irish television, Kenny said: “There is nothing to fear for voting for love and equality.”

Irish electoral rules prohibit any debate on the referendum to be broadcast in the 24 hours before polling stations open.

Supporters of the “Yes” campaign accused opponents of accepting funding from right-wing Christian groups in the US last weekend.

Under Irish law, it is illegal for lobby groups to accept foreign donations during a referendum campaign.

“No” campaigners have bought full-page advertisements in dozens of regional newspapers, calling on voters to reject marriage equality.

The “No” vote in Ireland is supported by US group the National Organization for Marriage (NOM), according to The Guardian.

NOM, which is headed by Roman Catholic Brian S. Brown, sent a letter to supporters around the world backing the “No” vote.

“Just like in campaigns for marriage here in America, slanted public opinion polls become fodder to influence and depress supporters of marriage,” The Guardian quotes the letter as saying.

“This is happening in Ireland. If [the ‘No’ campaign] can manage to pull off a victory, it will be a tremendous boost to the cause of marriage worldwide. Please do what you can to bring awareness to their efforts.”

However a NOM spokesperson denied the organization was funding opponents of gay marriage in Ireland.

Observers say the significant support for gay marriage shown in opinion polls demonstrates the waning influence of the Roman Catholic Church in Ireland after decades of scandals concerning child abuse.

Once a dominant political voice, a poll last weekend found that a mere 35 percent of people still rely on the Church to influence their vote. Critics of the Catholic Church in Ireland argue the true figure could be less.

Sequential Irish governments have long been viewed as socially conservative. The state only decriminalized homosexuality in 1993, following a ruling by the European Court of Human Rights.

In recent years, Ireland has seen a steady a rise progressive grassroots politics. Observers say a “Yes” vote on Friday will further highlight this trend.