Irish citizens are voting Friday on whether to amend the constitution to allow gay marriage in the socially conservative nation.
If the "yes" votes predominate in the referendum, Ireland would become the first country to approve gay marriage by popular vote.
In Europe, gay marriage is legal in more than a dozen countries. It has also been legalized in Argentina, Brazil, Canada, New Zealand, South Africa and Uruguay.
Public opinion polls in Ireland indicate support for same-sex marriage ranges from 53 to 69 percent, while support for a "no" vote is between 24 and 26 percent.
But the conservative Roman Catholic Church is a dominant force in Ireland, and many clergy have expressed opposition to a constitutional change. The secular Irish government, on the other hand, supports it.
A "yes" outcome is expected to depend on strong voter turnout, especially among young voters who historically do not vote in great numbers.
Homosexuality was not decriminalized in Ireland until 1993. And neighboring Northern Ireland, which is under British rule, has not joined the rest of the United Kingdom in legalizing gay marriage.
Results from Friday's day-long vote are expected by Saturday.