Former President Mary McAleese says Northern Ireland is changing towards having a nationalist majority.
On the day the UK was supposed to leave the EU, Professor McAleese said the Brexit process is driving a constitutional change both North and South.
Prof. McAleese said the backstop is not the most important element of protection for the Good Friday Agreement in the Brexit process.
Following the result of the Brexit referendum, then Taoiseach Enda Kenny secured an agreement with the EU that Northern Ireland would seamlessly re-join the bloc if the North and South were to reunite.
Prof. McAleese said it has always been known that the issue would come onto the agenda.
She said: "The issue of the ending of partition would come onto the agenda driven by demographics, the demographics in Northern Ireland are changing rapidly towards a Catholic/Nationalist majority.
"That's a reality that has to be taken into account, but Brexit put a different spin on things."
The former President does not believe the Good Friday Agreement would have been agreed if it had ever been envisioned that the UK would leave the EU.
She added that we need to learn from the Brexit process and iron everything out, including the softer issues, before going to the polls.
Prof. McAleese supported suggestions that a cross-border citizens assembly could be used to open up the debate on the future of the island of Ireland.