Leo Varadkar has said there's no Plan B if a programme for government is rejected this week.
He has suggested there will be a 'political crisis' if the deal doesn't pass.
Members of Fine Gael, Fianna Fáil and the Greens will continue to cast votes today ahead of the results being announced on Friday.
If they're approved, Micheál Martin will be elected as Taoiseach on Saturday.
In an exclusive interview with our political correspondent Sean Defoe, Fine Gael leader Leo Varadkar has admitted there isn't a back-up plan.
He said: "To be frank, there isn't.
“I know there are some people in my party who are counselling me and advising me to have a Plan B on the shelf, but I decided not to that because we entered these coalition talks in good faith with Fianna Fáil and the Greens.
"I thought it would be an act of bad faith to have a Plan B on the shelf so we don’t have that and [rejection] will precipitate a political crisis quite frankly."