Leo Varadkar was set to be elected Irish prime minister for the second time on Saturday, taking over from Micheál Martin under a novel rotation agreement struck between their two parties - once sworn rivals - in a 2020 coalition deal.
Martin resigned on Saturday ahead of a vote in parliament to elect Varadkar, who was prime minister from 2017 to 2020. Martin will become deputy prime minister until a scheduled 2025 election and is also expected to be appointed foreign minister.
The 2020 coalition deal - which also included the smaller Green Party - for the first time united Martin's Fianna Fail and Varadkar's Fine Gael, which are Ireland's dominant centre-right parties and have led every government since independence a century ago.
"This morning I visited the president and, pursuant to the relevant provisions of Bunreacht na hÉireann (Constitution of Ireland), I have tendered my resignation from the office of Taoiseach (prime minister)," Martin told parliament.
"It is both a privilege and a responsibility to serve as head of government in a free and democratic republic. I have been deeply conscious of this every day I have held the office of Taoiseach."
Varadkar will again face a years-long housing crisis that cost him a full second term in office and has made the left-wing Sinn Fein clear favourite to come out on top at the next election with a consistently wide lead in opinion polls, reports Reuters.