Micheál Martin's party is now hopeful of leap-frogging both Fine Gael and Sinn Féin to be the largest party in the country, and could even breach the 50 Dáil seat mark if the stars align.
This could be as many as 10 seats more than Fine Gael, which is now looking at returning around 40 TDs to the next Dáil.
But a good day in the count centres for Fianna Fáil could signal some very long and difficult days for government formation talks when counting is done.
Too wide of a seat rift between the two civil war parties calls into question the 'parity of esteem' arrangement that paved the way for a rotating Taoiseach and an equal divvy-up of the senior cabinet ministers last time around.
While it may not make it to 50, Fianna Fáil sources are now confident of landing somewhere in the high 40s, an estimation that is currently not shared by members of Simon Harris' party.
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Fianna Fáil sees itself losing around three seats, with Health Minister Stephen Donnelly missing out in Wicklow, junior Minister Anne Rabbitte losing her seat in Galway East and Joe Flahtery missing out in Longford Westmeath.
But in the case of Ms Rabbitte, the party seat will be retained and picked up by local party councillor Albert Dolan.
In Kerry, the party is in the hunt for two seats, with councillor Michael Cahill tipped to come in with outgoing Education Minister Norma Foley.
In Clare, senator Timmy Dooley, who lost his seat at the last election, is topping the poll, closely followed by party colleague Cathal Crowe.
The return of Pat the Cope Gallagher is being touted in Donegal meaning he will join Charlie McConalogue in the Dáil.
Another comeback is expected in Kildare South where Fiona O'Loughlin is on track to reclaim her seat after losing it in 2020.
There had been some controversy in Roscommon Galway when serving senator Eugene Murphy was not selected by the party to run, but this appears to have paid off for Fianna Fáil which is now on track to see Dr Martin Daly elected.
In Cavan Monaghan, the party will retain two seats, however, it could see the departure of Brendan Smith, who could be replaced by Fianna Fáil senator Robbie Gallagher. However, the eliminations of Aontú and Independent Ireland will decide which one of the two get across the line.
Senator Erin McGreehan will claim a seat in Louth, along with fellow senator Malcolm Byrne who is expected to get across the line in the newly formed Wicklow-Wexford constituency.
In Carlow Kilkenny, the party is expected to now pick up a third with Peter 'Chap' Cleere, former Kilkenny hurler, coming over the line with Jennifer Murnane O'Connor and John McGuinness.
In Tipperary North, 28-year-old Ryan O'Meara is expected to claim the seat vacated by Jackie Cahill.
Fianna Fáil has always had a weakness in the capital, but is set to make gains this time around.
In Dublin Mid-West, Shane Moynihan was in fourth place on first preference in the five seater constituency.
Having come close in 2020, Shay Brennan is now widely expected take a seat in Dublin Rathdown.
In Dublin South Central, senator Catherine Ardagh, who last time around was out canvassing just days after she gave birth to twins and eventually missed out on a seat, is looking more positive this time around.
There are outside chances of gains with Lisa Chambers in Mayo, Aisling Dempsey in Meath West and Teresa Costello in Dublin South West.
It all of this paves the road to the magic 50, if the transfers fall right, but in doing so it is storing up problems for the weeks ahead.