The Tánaiste Simon Coveney will head up the Fine Gael negotiating team when talks on a new confidence and supply arrangement with Fianna Fáil get underway next week.
Leo Varadkar announced the appointment on his way into the EU Leaders Summit in Brussels this afternoon.
The leaders of both parties met on Monday and agreed to begin talks in the coming days.
Fianna Fáil leader Micheál Martin has called for the talks to include a review of the arrangement that has kept the minority Government in place over the last three budgets.
For his part, Mr Varadkar has called for an extension and an agreed 2020 date for the next election.
Both sides have agreed not to bring down the Government while Brexit remains in the balance.