Irish Prime Minister Enda Kenny on Wednesday said he will step down once a new leader for his Fine Gael party is elected by June 2 at the latest.
"I will retire as leader of Fine Gael effective from midnight tonight," Kenny said, opening the way for a swift leadership contest.
In a statement on his way into a parliamentary party meeting on Wednesday evening, Kenny said he would continue as prime minister pending the election of his successor.
"I will continue to carry out my duties as party leader in an acting capacity until my successor is elected," the 66-year-old said.
"I have asked that the Fine Gael executive council expedite this process and to have it concluded by close of business on Friday June 2."
Kenny is the longest-serving member of the Dail, the lower house of parliament, having first been elected in 1975.
He has led the centre-right Fine Gael party for 15 years and been prime minister since 2011.
He is the first Fine Gael leader to win re-election to office.
Two candidates have so far declared an interest in becoming the next party leader and, by default, the next prime minister for the remainder of what is widely considered to be a fragile, minority government.
Leo Varadkar, 38, may appear an unlikely front-runner in what is still regarded as a socially conservative, relatively homogeneous country.
The Dublin-born son of an Indian immigrant father and Irish mother became the first overtly gay cabinet minister when he declared his sexuality in a national radio interview in 2015 and has campaigned on issues such as same-sex marriage and more liberal abortion laws.
The high-profile social protection minister practised as a doctor before winning a seat in 2007 and has rapidly risen through the ranks to hold several ministerial portfolios.
His rival Simon Coveney, 44, fits the more traditional profile of a Fine Gael leader and is steeped in politics.
He was first elected to parliament in 1998 following the death of his father who had held the Cork South-Central seat before him.
The current housing minister has also been in charge of several portfolios including agriculture and defence. He is married with three daughters.