The Taoiseach Enda Kenny is coming under parliamentary pressure to set up an all-island forum to deal with Brexit despite a "humiliating" rejection from the North's First Minister.
Mr Kenny said his invitation for an "island conversation" remains open to political parties and other organisations north and south but warned it would be divisive without cross-party agreement.
Arlene Foster, Stormont First Minister whose Democratic Unionists campaigned for a Leave vote, publicly dismissed the suggestion after a meeting of the North South Ministerial Council on Monday.
In the Dáil, Mr Kenny was accused of having botched the idea by floating it over the weekend without consulting Ms Foster.
Labour leader Brendan Howlin said the Taoiseach's approach had "damaged" the authority of his office and "more importantly the interests of Ireland".
"At yesterday's press conference it became clear that the Taoiseach had failed to prepare the ground with the Northern Ireland First Minister and the result was that the proposal was rejected by her publicly in a very humiliating way," he said.
Micheál Martin, leader of the chief Opposition party Fianna Fail, said he found it incredible that the proposed forum was trumpeted by Government ministers over the airwaves without consultations with Stormont.
The approach resembled a "shambles", he told the Dáil.
"Very clearly now the will of the people of Northern Ireland is going to be subverted by the English nationalistic approach in terms of its future within the EU," he said.
"Brexiters have very little time for Northern Ireland, to be frank, and Northern Ireland will not be central to their engagement with Europe.
"We do need an all-island response here. But we need to work in advance before people start floating ideas just for the sake of spin over substance."
Some 56% of voters in the North backed remaining within the EU. The DUP was the only major party on the island to campaign for a Brexit.
Mr Martin said a majority of people in the North voted to stay in the EU and that "additional capacity" is needed in government departments on both sides of the border to work towards that.
Mr Kenny said it was no time for political point-scoring and called on everybody to work together.
"It was a good idea and still remains a good idea," he said of the proposed all-island forum.
"And I keep open an invitation to everybody if they want to follow through on it."
Mr Kenny said the forum would not be a statutory authority and could not work if other parties did not buy into it.
But Gerry Adams, who said he first proposed the idea in a letter to all leaders last week, insisted a DUP rejection "should not be allowed to stand in the way of such a body".
The Sinn Fein leader said the DUP had previously opposed the Good Friday Agreement.
"There is actually an opportunity in all of these difficulties to redesign the future of the island of Ireland and of the EU," he said.
"But let's redesign the future of the island of Ireland first and the way to do that is to put together the forum."
Mr Adams claimed "civic unionism and civic society in general" would attend the proposed talks.