Sinn Fein would demand a border poll in any proposed coalition after the next election.
Mary Lou McDonald told her party's Ard Fheis last night that a vote on Irish unity needs to happen within five years.
The Sinn Féin leader said it's time to consider what the next decade will mean for a united Ireland.
Deputy McDonald told the conference that the Government needs to convene an all-Island forum to map a transition to a united Ireland.
Sinn Féin Ard Fheis 2019 Presidential Address https://t.co/8wDt6R2GX7
— Sinn Féin (@sinnfeinireland) November 16, 2019
She also told delegates that the people of Ireland had been "short-changed" by Fine Gael and Fianna Fáil.
She said they needed a new deal to tackle the "crushing cost" of living and increase income.
The party is also pledging to reduce rents by up to €1,500 a year through tax relief and a three-year rent freeze.
Mary Lou McDonald said the crisis in housing and the health service would only be solved with Sinn Féin in government.