Almost three-quarters of respondent to a new opinion poll have said they are in favour of same-sex marriage.
The country is expected to go to the polls on May 22 when people will be asked to vote in the marriage equality referendum.
According to the new survey, if the ballot was held today an over-whelming majority of 73% would say 'Yes'.
However, 22% of people would say 'No', while a further 5% don't know how they feel about it.
The Behaviour & Attitudes poll, which appears in today's Sunday Times, interviewed almost a thousand adults between Monday, March 2 and last Wednesday.
Brian Sheehan, from Yes Equality, says campaigners need to make sure they do not become complacent after today's result.
"Irish people take constitutional change very seriously, we all do and all have in all the constitutional amendments we've been asked to vote on," he said.
"As the debate, if you like, accelerates in the couple of weeks coming up to the referendum, people focus deeply on the issues in a way that they may not be at the moment, and I think that's the time when we realise that every single vote will count on the day.
"The divorce referendum passed only by the equivalent of one vote in every ballot box."