Gerry Adams has announced his intention to stand down as Sinn Fein president in 2018.
The republic veteran was speaking in Dublin on Saturday evening and an announcement on his retirement was widely expected.
He goes before the annual Sinn Fein Ard Fheis to seek re-election every year and earlier on Saturday he was elected unopposed.
But the 69-year-old, who has been the party president since 1983, told delegates it would be his last as leader, and a special meeting of the party would be called next year to elect a successor.
He also said he would not be standing in the next Dáil election in the Republic of Ireland.
"Leadership means knowing when it is time for change and that time is now," he told the annual conference in the RDS arena in Dublin.
In his speech he said that he and his long-term party colleague and friend, the late Martin McGuinness had made plans to step aside.
"Ten years after entering government with Ian Paisley, Martin’s intention was to step down as deputy first minister on 8 May. Then life punched us in the face with Martin's passing," he explained.
"Martin was a leading member of our leadership team. I have been enormously privileged to be part of an amazing and evolving collective leadership."
The long-standing MP for west Belfast switched his focus to the Dublin parliament in 2011, becoming a TD for Co Louth.
Sinn Fein has made steady gains in the Irish Republic in recent polls but many believe the prospects of further growth is limited due to the presence of Troubles era figures.
Current deputy leader Mary Lou McDonald, 48, will be a clear favourite to succeed Mr Adams.
The Ard Fheis also saw the party faithful debate its position on abortion, with delegates voting to partially liberalise the party's stance ahead of next year's referendum on the constitution's strict rules on terminations.