On the evening of April 6, 2016, Enda Kenny met Micheal Martin in a small room located between Government Buildings and Leinster House.
During the hour-long rendezvous, the then Taoiseach offered the leader of Fianna Fail a five-year partnership government with a rotating Taoiseach, and equal number of cabinet ministers.
Mr Kenny left the meeting believing his offer had got a fair hearing and returned to brief his senior ministers, including Leo Varadkar on what had happened. "He didn't rule it out!" Mr Kenny told them as he walked in the door.
Mr Martin talks very dismissively of that offer now, but at the time he slept on it and didn't actually rule it out until he met Mr Kenny for a second time the following day. The meeting was shorter, breaking off after 10 or so minutes. Mr Martin said he rejected it in the national interest, saying the offer left "a lot to be desired" and was "driven by narrow party interests".
It was another month before a Fine Gael-led minority government was eventually formed after the two parties cobbled together a confidence-and-supply deal following protracted talks in Trinity College that were dominated not by the crises in health and housing but how they would scrap water charges.
The alliance between the two largest parties in the State endured, against the odds and aided by the Brexit uncertainty, for just under four years. The opposition, particularly Sinn Fein, have in that period dismissed the arrangement as effectively the two parties governing together.
But it has also prompted serious figures in both parties to consider more openly the possibility of actually going into government together, including party grandees on both sides.
In October 2017, former Fianna Fail finance minister Ray MacSharry even claimed that he discussed the idea of a merger of the two parties with Michael Noonan in the 1980s.
"There was quite a level of agreement about it at the time, but the heads [party leaders] wouldn't hear tell of it and still won't," Mr MacSharry told me. For what it's worth, Mr Noonan, who has retired from politics, said in 2016 he would "never" go into Government with Fianna Fail.
Last week Mr MacSharry was more reserved and on-message. "Fianna Fail have ruled it out and I think they're right. It's not going to be easy to ever make that arrangement unless you have a long-term government for five years," he said.
His son Marc MacSharry, who is running for re-election in Sligo-Leitrim, was in favour of the grand coalition offer in 2016, as were others in Fianna Fail at the time, including TDs John McGuinness and Bobby Aylward.
In this election Mr Martin's firm rejection of the idea is parroted by his deputies and candidates who are keen to maintain discipline in the campaign.
Privately, they are a bit looser about the reality that could face them if Fianna Fail does not have sufficient numbers to form a government with smaller parties and Independents. Incidentally, the same applies among some Fianna Fail TDs when it comes to the idea of coalescing with Sinn Fein.
The past four years was not the first time Fine Gael and Fianna Fail have co-operated. Between 1987 and 1989, Charlie Haughey's Fianna Fail minority government was supported in Dail votes by Alan Dukes's Fine Gael under the so-called Tallaght Strategy.
Mr Dukes told the Sunday Independent that he believes grand coalition could become "the only viable option" after this election. "I used to worry that it would solidify the left, but the way they are performing, they are a long way away from becoming a coherent voice.
"If that's the case then why not have the grand coalition. I think both of the larger parties will find that somewhat less objectionable than going in with Sinn Fein."
In Fine Gael there is growing support for the idea at all levels, which is indicative of the party's seemingly growing acceptance that it will not be in a position to form a government after next weekend. Party figures argue that the country will need a stable government as the Brexit trade talks enter a crucial phase.
Fianna Fail thinks differently, of course, with Mr Martin straight-out rejecting Mr Varadkar's idea that it would be a coalition of last resort if all other options for government formation failed. Mr Martin remains supremely confident of his ability to have enough seats and enough support among smaller parties and Independents to put together a government. But if he doesn't he will have to look elsewhere to fulfil his ambition to be Taoiseach.
This weekend he is not ruling out Fine Gael supporting him under a confidence-and-supply deal.
Figures in both parties are more concerned about the rise in support for Sinn Fein than ever before, acknowledging that the surge in the polls is evident on the ground. "There is definitely Sinn Fein growth," said a senior Fianna Fail figure.
If they are both to remain true to their word of not doing a deal with Mary Lou McDonald then they may have to seriously think about sitting down with each other once again.
Politics, and more specifically government formation, is and will forever be about numbers and after voters go to the polls on Saturday they expect their elected politicians to give them a government - not a second election
Just as in 2016, it may take 70 days and many false dawns for that reality to hit home amongst senior politicians. But when it does, don't be surprised if it involves the big two doing another deal of some sort and if that is the case it will make the argument against a full-blown grand coalition increasingly redundant.