A new Red C/Paddy Power opinion poll on the fiscal treaty shows a relatively stable proportion of voters favouring the Yes side, which would be enough for the treaty to be passed.
However, compared to the last Red C Poll published a week ago, it suggests a slight shift towards undecided voters.
The poll of over 1,000 voters suggests the Yes vote is down from 53% to 50%, while the No vote remains unchanged at 31%.
The percentage of undecided voters has increased from 16% to 19%.
The poll shows support for the treaty lies primarily among the 55-plus age groups and in groups residing in Dublin and the rest of Leinster.
Just under two thirds of the population (59%) claim they will definitely vote in the referendum at the end of this month.
'No second vote'
Fine Gael's director of elections Simon Coveney has insisted that there will be no second referendum on the fiscal treaty if Irish voters reject it later this month.
He said Minister Richard Bruton's comments yesterday evening, in which he seemed to indicate that a re-run of the referendum was possible, were a "mistake that caused confusion".
Minister Bruton later retracted the comments, which he said were made in the heat of debate on radio.
Speaking on RTÉ’s Morning Ireland, Mr Coveney insisted that the Irish people will only have one opportunity to vote on the treaty.
"This will be a one-off referendum and people need to know that when they make a decision at the end of this month, because it is an important decision for themselves and the future of their country.
“People should not be assuming that they can vote in one way and force the Government to go back and renegotiate because there will be a second chance, because there won't be a second chance."
On the same programme, Independent TD Thomas Pringle said it is the Government's clear intention that if the people vote the "wrong way" in the referendum that they will "force the issue" again.
Mr Pringle said Mr Bruton's comments were made in a considered way in response to a question and not made in the heat of debate.
He said he did not accept the clarification and that the Fine Gael/Labour coalition was no different from the previous Fianna Fáil-led Government.
Mr Pringle said: "If you actually listen back to the comments that Richard Bruton made they were made in a quite considered way in response to a question.
"It wasn't that it was in the heat of debate that he might have slipped and said something he might regret afterwards.
''The intention is clearly there that if the people vote the wrong way for the Government that they will force the issue again and force people to vote again on it."
The Taoiseach has also insisted that there will not be a second referendum.
Enda Kenny described the referendum as a crucial decision for Ireland's future and an opportunity for the country to take another step towards economic recovery.
He said a Yes vote is the best way of ensuring that investment in jobs continues and grows.