The Yes side retains a commanding lead in the campaign to amend the constitution to permit same-sex marriage but the decline in support revealed in the latest Irish Times/Ipsos MRBI poll suggests that the outcome could be close.
Voters are due to go to the polls on May 22nd and with the real campaigning yet to begin, the decline in support for the Yes side since the last poll shows that the Government has no grounds for complacency.
Support for a Yes vote remains strong at 74 per cent but this is down six points since the last poll in December.
Campaigners for a Yes vote will be aware that polls in advance of referendums have frequently overstated the support for constitutional change by a considerable margin.
For instance just a week before the referendum on the abolition of the Seanad in autumn 2013 the Irish Times poll indicated that 62 per cent of voters would vote Yes and 38 per cent No. The proposal was defeated by 52 per cent to 48 per cent.
The findings of the latest poll, which is the first to show a decline in support for the Yes vote since The Irish Times began to measure the public mood on same-sex marriage in 2012, reveals a big difference in voting intentions across the age groups.
While there is overwhelming support for the Yes side among younger voters, the level of support declines with age.
The No side has a lead among voters over 65 with 43 per cent saying they will vote against and 37 per cent saying they will vote for the amendment.
The over 65s are the only age cohort where a majority intend to vote No at this stage but the highest turnout in referendums and elections is usually from this group.
In class terms the best-off AB voters are the most inclined to vote Yes with the poorest DE category less supportive.
Farmers are the only social group where the No side is ahead but there is no marked difference across the different regions of the country.
There is a significant gender difference with women more inclined to vote Yes than men.
In party terms Fianna Fáil supporters are the least enthusiastic with Labour voters the most supportive of a Yes vote.
Among Labour voters 80 per cent intend to vote Yes and 15 per cent No. Among those supporting Independents and smaller parties, 71 per cent say they will vote Yes and 20 per cent No.
Sinn Féin supporters are almost equally supportive of a Yes vote with 70 per cent in favour and 17 per cent against.
Fine Gael voters are significantly less enthusiastic with 59 per cent Yes and 27 per cent No. Fianna Fáil voters are the least enthusiastic of all with 54 per cent Yes and 34 per cent No.
In the other referendum on May 22nd it looks as if the Government proposal to reduce the age for presidential candidates will be defeated.
Asked how they intended to vote on the proposed amendment 62 per cent of people said No, 29 per cent said Yes and 9 per cent were undecided or said they would not vote.
The proposal, which emerged from the constitutional convention, is opposed by all age groups apart from the 18 to 24 cohort. Even a significant majority of the 24 to 35 age group intends to vote No.
Opposition to the amendment is strong across all regions with the biggest No majority in Dublin and the lowest in Connacht-Ulster.
It is the same across the class divide with strong opposition across all social categories with the poorest DE group a little less strong than the others.
In party terms Fine Gael and Labour supporters are the strongest opponents of the move being proposed by the Government. Some 71 per cent of Labour voters and 68 per cent of Fine Gael voters intend to vote No.
Fianna Fáil and Independent voters are a little less vehement in their opposition while Sinn Féin voters are the only ones among whom there is relatively strong support for the move with 50 per cent of them in favour and 41 per cent against.