Former taoiseach Bertie Ahern has said a huge amount of "preparatory work" needs to be carried out to prevent any Border poll in the North from resembling the failed Scottish referendum.
In an interview on the Anton Savage Show on Newstalk, Mr Ahern said that in the run-up to Northern Ireland's Assembly election there was "very little talk" by nationalist parties about a Border poll or about unity.
He said although the election was about "economic bread-and-butter issues of the day" , the issue of a united Ireland "is continually on the agenda".
“It is on the agenda since 1998. The provisions for having a Border poll is there,” he added.
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Mr Ahern acknowledged that Sinn Féin has moved to a position on the issue which he said he has been articulating for a long time – “that you don’t have that poll until the work is done”.
He said some of the academic preparatory work is under way, and added there is no point in having an election “until you work out what does unity mean? What kind of a new Ireland is it? How would you bring it all together?”
He said: "The Scottish referendum proved that . . . they hadn't worked out the cost issue and how you were going to fund an independent Scotland. "
He said there was economic and practical work to do: “How it would be paid for? How long would the British continue to pay? Would you still have an Executive in Northern Ireland? Would there still be a regional Executive?”
Mr Ahern said there were also “fundamental” issues such as policing, the courts, public administrations and semi-State companies that needed to be looked at.
He added: “The fact is that none of this has been thought through. We have been yapping about it for years but it hasn’t been done. It has to be done otherwise you are asking people to vote in an entire vacuum. What happens when you do that it that people vote no.”
Unionism
Mr Ahern also said efforts need to continue to be made to reach out to the unionist community in the North, despite any lack of engagement: "Their view is for them to even engage in that vote is a mistake. Because once they get in to that debate, even participating in that debate, they are accepting that there could be a change from their beloved union with the United Kingdom. That is their position.
“In building a new Ireland you have to try and reach out and bring in as many people of unionist tradition as you possibly can. But the concept that you will be able to bring in the entire lot will never happen.”
Mr Ahern said the Irish Government should now try to move in to Governmental conference level under the Belfast Agreement to try to engage with the British government.
He reiterated remarks from Minister for Foreign Affairs Simon Coveney that the partnership and co-operation the State had with the British government has "lapsed".
Mr Ahern said the focus once the Executive is up and running should be trying to find a solution to the Northern Ireland protocol, which allows goods to flow freely between the North and the Republic to avoid a hard border.
Meanwhile, Mr Ahern added that Fianna Fáil is facing a "big challenge" in the coming years against Sinn Féin.
He said: “Fianna Fáil need to be re enacting their ability to organise themselves, attract candidates and have policies. As it stands now Sinn Féin are in a very strong organisational position right across the Republic . . . There is a big job to be done.”