POLITICAL leaders from Sinn Féin and the SDLP have endorsed an open letter signed by more than 3,000 Antrim Gaels calling for planning around an "agreed shared Ireland".
Michelle O'Neill and Colum Eastwood also said the time for discussion about constitutional change has been hastened not just by Brexit but the fallout from the Scottish election results, with pressure mounting for a second independence referendum.
The letter, which was published in Saturday's Irish News along its full list of signatories, was sent to Taoiseach Micheál Martin.
It calls on the Irish government to establish an all-island citizens assembly "reflecting the views of citizens north and south to achieve maximum consensus on a way forward".
Ms O'Neill congratulated the Antrim Gaels on the initiative and said its timing was important.
"There is an evolving conversation and public discourse on future constitutional change, of which Brexit has been a catalyst - both in Ireland, but Scotland too with pro-independence majority government elected in recent days," the Sinn Féin northern leader said.
"The world is moving on. The political landscape is changing rapidly. Preparation, planning and dialogue are key.
"We must persuade those who fear constitutional change that through our actions that there is a future in our common interest that we can shape - a future beyond Brexit, and one beyond the union."
Antrim GAA footballers, hurlers and camogs are among those openly supporting the campaign, with all-Ireland winner and former camogie All Star Jane Adams saying the Irish government "needs to take a lead role in this" and begin planning for a border poll.
Mr Eastwood said the letter highlighted growing calls across civic society for a "wide ranging debate about our future".
"It's not based on righting historic wrongs but a genuine desire to talk about how we can build a society that meets the needs and ambitions of all our people. The impact of Brexit and the move toward a second independence referendum in Scotland has made more and more people impatient for change," he said.
"Those who believe in constitutional change across these islands now need to put in the hard yards to detail what that means for jobs, schools, health services and everything that’s important to people across our communities. And we need to reach out to have the conversation, without predetermined outcomes, with our unionist friends and neighbours."
Former Antrim senior footballer Paddy Cunningham, who is spearheading the project along with Ms Adams, said he hopes the letter is a "good starting point to encourage and develop meaningful debate amongst Gaels and to encourage the Irish government to plan for constitutional change."
High profile signatories include former hurling star Terence McNaugton, ex-footballer and MND campaigner Anto Finnegan and solicitor Niall Murphy.