Former Sinn Fein President Gerry Adams has been appointed the party's spokesperson on Irish unity.
The move was announced after current President Mary Lou McDonald reshuffled the party's Dail front bench team.
Mrs McDonald announced a number of changes to her team, including the appoint of Sean Crowe as Brexit spokesperson in place of David Cullinane.
She said the reshuffle would "renew focus and direct that talent outwards as we face into a new Dail term and all the challenges that will bring".
Mr Adams stood down as Sinn Fein leader in February 2018 after more than 30 years in the role.
The Louth TD said that he would not be seeking re-election at the next general election and took up a reduced role in party life.
The move brings the veteran republican back into the party's front-line team.
Mr Adams has never shied away from publicly discussing the party's ambition of Irish unity, and has often taken the lead on the issue, even after leaving office.
Last month Mr Adams said that Irish unity should not be rushed into without a proper plan.
Writing in his blog, Mr Adams said he was confident that there will be a referendum on a united Ireland and called on the Irish government to open up the consultation needed to plan for it.
But he added there should be a transition phase in the event of a successful vote for Irish unity.
This needs planned now. Not after the referendum. That is the one big lesson of Brexit: a referendum without a plan is stupid," he wrote.
"So a referendum on unity must be set in a thoughtful inclusive process which sets out a programme of sustainable options. Including phases of transition."