Counting of Fine Gael and Fianna Fáil postal ballots begins this morning as the country prepares to find out if a government will be formed.
All three parties will announce their results early this evening, with Green Party ballots set to be counted after midday.
To pass the programme for government, Fine Gael will only need all of its parliamentary party, which makes up 50% of the total poll, to have approved the deal, though party sources say they are confident that the deal will pass "resoundingly".
For Fianna Fáil, a simple majority of the votes returned from their 18,000 or so members will be needed. Sources in that party are confident the deal will pass, with some estimating that around 65% of members will have voted Yes.
For the Greens, the bar is higher which makes their poll the one which people in all parties will be watching the closest. The Greens' 3,000 members will need to pass the deal with a two-thirds majority in order to send Éamon Ryan's party into coalition with the Civil War parties.
A Green Party source said that it "could go either way" and that today would be "tense".
If the deal is approved, a special Dáil sitting tomorrow would see Mícheál Martin elected as Taoiseach in Dublin's Convention Centre.
However, any idea of a contingency, where Fine Gael and Fianna Fáil attract the votes of enough independents to get a Taoiseach elected has been played down in recent days.
Taoiseach Leo Varadkar has said there is "no Plan B" to the deal, though a fully constituted Oireachtas is needed in order to renew the Offences Against The State Act and legislation related to business supports.