The leaders of Fianna Fail and Fine Gael have said negotiating teams for both parties are set to start "in-depth, detailed talks".
In a joint statement, both parties said they have held constructive discussions over the past two days about policy issues and the political situation.
They have said they will also continue discussions with the Green Party.
Two identical statements said Leo Varadkar and Micheal Martin are "acutely aware of the enormous challenges facing the country" with the onset of Covid-19.
It said both parties will enter the talks as equal partners.