The Yes side retains a commanding lead in the referendum campaign on same-sex marriage, according to the latest Irish Times/Ipsos MRBI poll, but the gap has narrowed since the last poll in March.

When undecided voters are excluded, the poll indicates that 70 per cent of voters intend to vote Yes (down four points since March) and 30 per cent say they will vote No (up four points).

The poll was taken last Wednesday and Thursday, with a just a little over a week to go before the vote.

Asked how they intend to vote in the referendum to change the Constitution to allow same-sex marriage, 58 per cent said Yes (down six points); 25 per cent said No (up two points); and 17 per cent were undecided or said they would not vote (up five points).

It is the second Irish Times poll in succession to show a decline in support for the Yes side. There has been a small shift into the No camp and a more sizeable one into the “don’t know/won’t vote” category since the last poll.

120 sampling points

The findings show a marked difference in voting intentions between young and older people. Among 18- to 24-year-olds, 71 per cent intend to vote Yes and 15 per cent No. By contrast, in the over-65 age group, 52 per cent intend to vote No and 34 per cent Yes.

There is a also a significant gender difference, with women more inclined to vote Yes than men.

In party terms Fianna Fáil supporters are the least enthusiastic for a Yes vote and Labour voters are the most supportive.

Asked if they were still listening to both sides of the argument or had made up their minds on the issue, 79 per cent said they had made up their minds. Just 20 per cent said they were still listening.

The response to this question indicates it will take a seismic shift in the last week of the campaign to overturn the lead held by the Yes campaign.

If the younger age groups come out to vote, the referendum will be carried, but if there is a low turnout the outcome could be close because the over-65s traditionally vote in large numbers.

In the poll, voters were also asked a number of questions in an effort to determine their motivation for voting Yes or No.

Consider children

There was a substantial difference in attitudes among those who described themselves as religious and those who did not. Among No voters, 75 per cent of them said they were religious while 45 per cent of Yes voters said they were religious.

The biggest reason for voting No, cited by 82 per cent of those who intend voting against the proposal, was that it would diminish the importance of marriage. Just 11 per cent of Yes voters agreed with that proposition.

Asked if they felt they could not openly discuss the issue, 28 per cent of No voters fell into this category, while just 9 per cent of Yes voters took that view.

The other referendum next Friday, the proposal to reduce the age for presidential candidates from 35 to 21, looks set for a heavy defeat.

Asked how they intended to vote, 64 per cent of people said No (up two points on the last poll), while 23 per cent said Yes (down four point) and 12 per cent were undecided or said they would not vote (up three points).

Undecided

The proposal, which emerged from the constitutional convention, is opposed by all age groups – including those between 18 and 34, at whom it is aimed. In party terms, Fine Gael supporters are the strongest opponents of the move.