The Tánaiste Leo Varadkar is set to replace Micheál Martin as Taoiseach later today.
The position of Taoiseach is being rotated for the first time in Irish political history.
Mr Varadkar will be named Taoiseach for the second time following a vote of the Dáil.
The switchover is part of a deal between the governing coalition parties that will see Mr Varadkar take charge again.
How the day will work
It will be a busy Saturday for political leaders amid a change of leadership, as well as a Cabinet re-shuffle.
Later this morning, Mr Martin will head to Áras an Uachtaráin to meet President Michael D Higgins and resign.
The Dáil will then sit for the election of Leo Varadkar - the first time Fianna Fáil TDs will have to stand up and vote for a Fine Gael Taoiseach.
It is a moment unprecedented in Irish politics, and one Mr Martin has said was born out of pragmatism.
Old rivalries were largely put aside for the past two and a half years, but the time to come will test the strength of the coalition.
Following this. the new Taoiseach will go to Áras an Uachtaráin to be appointed.
Calls will then go out as the new Cabinet under the new Taoiseach takes shape.
Few changes are expected, with all eyes on what department Mr Martin wants.
It is expected he will become Foreign Affairs Minister, with Simon Coveney likely to move to Enterprise.
Paschal Donohoe and Michael McGrath will also swap the Finance and Public Expenditure briefs.
Later the appointment of Government Ministers will take place back at Áras an Uachtaráin.
President Higgins will sign the Warrant of Appointment for the members of the Government, as well as the Warrant of Appointment of the Attorney-General.
The President will then present each minister with their Seal of Office, and the new Cabinet will hold its first meeting at Áras an Uachtaráin.
Reporting by: Sean Defoe