Irish Prime Minister Enda Kenny has stood down as leader of Fine Gael.
He will continue as taoiseach (prime minister) until the Dáil (parliament) chooses a successor.
Mr Kenny, who was elected taoiseach in 2011, tendered his resignation in March, but has been acting prime minister since then.
He told a parliamentary party meeting on Wednesday that a successor would be appointed by 2 June.
The 66-year-old had been under pressure to resign from factions within his own party that were dissatisfied with his leadership.
‘Honour and privilege’
The Fine Gael leadership contest will begin on Thursday, with nominations closing on Saturday.
A new leader to be announced after an electoral college of the parliamentary party, county councillors and party members have their say.
The two favourites are Leo Varadkar, who is the son of an Indian immigrant, and Simon Coveney, whose father was also a government minister.
In a statement announcing his retirement as leader, Mr Kenny said it had been a “huge honour and privilege” to steer the party over the course of 15 years.
He added that he will “continue to carry out my duties and responsibilities as taoiseach” until his replacement.
‘Strength to strength’
UK Prime Minister Theresa May said Mr Kenny had been a “strong and consistent friend” to her country.
“I want to thank him for all he has done to maintain the unique and close spirit of co-operation between our two nations, which has gone from strength to strength during his time as taoiseach,” added Mrs May.
Her predecessor David Cameron said Mr Kenny “was a strong leader for Ireland, a great partner for the UK, and remains a good friend”.
Sinn Féin president Gerry Adams said Mr Kenny “did his best from his perspective” but his “political legacy is dominated by crisis, chaos, and chronic lack of accountability”.
Among Mr Kenny’s final official overseas engagements will be a two-day trade mission to Chicago and the centenary commemoration of the start of the World War One Battle of Messines.