Kenny said he would give his successor a "brief but appropriate" time to hold talks with parties and independents propping up the minority administration, "regarding the provision of government for the future".
— Enda Kenny (@EndaKennyTD) May 17, 2017
15 years a leader
Kenny, prime minister since 2011 and the leader of his centre-right party for almost 15 years, is expected to be replaced by a younger colleague - most likely Social Protection Minister Leo Varadkar, the bookmakers' favourite, or Housing Minister Simon Coveney.
Kenny, 66, is credited with steering Ireland out of its economic collapse, but domestic scandals and a slump at the ballot box saw him come under pressure from within Fine Gael to step aside.
Fine Gael lost seats but narrowly remained the largest party after the February 2016 general election as the austerity imposed to turn around the 2010 economic crash grated with growing numbers of voters.
Kenny has faced criticism over his cabinet's handling of a case involving a police whistle-blower and the government survived a no-confidence vote in February.
.@EndaKennyTD was a strong leader for Ireland, a great partner for the UK, and remains a good friend.
— David Cameron (@David_Cameron) May 17, 2017
Can I just say to all the #endakenny haters who are celebrating.. the country is in a lot better state now than before he took over.
— Jeremy Dixon (@JeremyDixonDJ) May 17, 2017