People should have their say on a united Ireland "in this decade", the Sinn Féin leader has said.
Mary Lou McDonald was speaking today at her party's Ard Fheis in Athlone.
Britain's Northern Ireland Secretary Hilary Benn has previously ruled out a border poll on a united Ireland as there is “no evidence” the majority of people there would support it.
In February a survey by the Belfast Telegraph and LucidTalk found 49% of people would vote to stay in the UK in a border, compared to 39% who would vote for a united Ireland.
The survey also found that the majority of people under-45 support a united Ireland.
Ms McDonald said there needs to be preparatory work in both Dublin and London.
"Irish reunification for us represents a massive opportunity," she said.
"It's not a Sinn Féin thing, it's not just simply a republican issue, this is for everybody who lives on this island.
"The case is, in my opinion, unanswerable for constitutional change.
"What we want to do is to have that democratic conversation that makes space for everybody, where you listen to everybody, where you consider every point of view."
'In this decade'
Ms McDonald said those against the idea of a united Ireland should "open your mind, just listen - just give it a fair listen."
Ms McDonald said she believes a united Ireland is "closer than ever".
"We have called this the decade of opportunity - I think people North and South have to have their democratic opportunity in this decade," she said.
"I think that can happen, we're going to work very, very hard to make that happen.
"We will live in a united Ireland."
Ms McDonald said language is also important when discussing a united Ireland.
"I really am so concerned that when we talk about this subject that it's not in language of loss or threat - this is about opportunity and additionality," she said.
Ms McDonald said unionist communities in Northern Ireland should also consider the next steps.
"I know that unionists will set out a unionist position - I think they need to do that," she said.
"I don't think they should just take it for granted that the union is the default position - there are choices here, there are options now."
'Action point for Government'
Ms McDonald said both governments need to make unification into an objective.
"For that to happen the Government in Dublin has to move beyond rhetoric to actually making this an objective.
"Not just that but [also] an action point for Government - and London too".
Ms McDonald, who recently attended the UK Labour Party conference, said the referendums will happen eventually.
"It's not a credible or sustainable position for [British Prime Minister] Keir Starmer to put it on the 'never, never' [list]," she said.
"Referendums are provided for in the Good Friday Agreement, it's now 26 years old.
"The referendums are going to happen - the challenge politically for leaders, whether you're a unionist or republican, whether you're in the North or the South - is preparation for those referendums.
"We want [an] orderly, democratic and entirely peaceful transition from partition to reunification.
"I think it's a really exciting time".
A report from the Institute of International and European Affairs (IIEA) has previously said that a united Ireland would only be possible with a dramatic increase in taxation or a major reduction in public spending.
Northern Ireland is shown on a map, 19-3-21. Image: GH Maps / AlamyOn a general election, Ms McDonald said she believes it could be sooner than November.
"I think it's coming very soon - I still think it's probably November although we're advised, and the chatter is, it could be sooner," she said.
"Whenever it comes... we're ready and we're going out to set out the real opportunity now for people here for change.
"We've had 14 years of Fine Gael in government, we have a housing crisis, we've childcare costs still through the roof, a cost of living crisis that people are struggling through.
"Sinn Féin now has a really solid policy platform - we have plans and we want to get the chance to deliver them."
She added that she believes "the general public is ready now for an election too".
