I still haven’t recovered my composure after getting up early to watch Ireland play probably their greatest ever rugby match on Saturday morning. I’ve even watched a replay of the match several times, because I find it almost incomprehensible that ordinary humans could dig that deep.

The stories emanating from the dressing room after the match told their own tale: Of a team determined to do themselves and their country proud, a group of men who knew they hadn’t given of their very best — and that nothing but their best would be enough and players whose bond was as strong as it could possibly be.

That’s how history is made, by people prepared to put everything on the line for a vision and a sense of purpose. It’s made by people who trust in each other and are ready to sacrifice for each other.

And then on Sunday afternoon I watched history being made again. Dublin beat Kerry with five minutes to go in the All-Ireland Final. They capitalised ferociously on a couple of defensive errors, and they did the impossible. Deadly accuracy, sweet finishing, impeccable timing. They breathed new life into a competition where the outcome had seemed predictable, even boring. They refused to be beaten. Even (a few!) Kerry people left Croke Park smiling.

And just when I thought it wouldn’t be possible to pack any more history into one weekend, Fianna Fáil crossed the Rubicon. They took a giant step towards complete oblivion. No teamwork here. No digging deep. No trust. Just awful timing, endless defensive errors, no pride. Not just are they willing, it seems, to be beaten, they have simply walked off the pitch. And it’s virtually impossible to see how they can recover.

Fianna Fáil’s dithering over the presidential election has been daft from the beginning. A political party that wants to be taken seriously, especially a party that has always regarded itself as genuinely national, must contest national elections. Of course the chances of Fianna Fáil winning this particular presidential election have always been somewhere between slim and none.

But in Brian Crowley they had a candidate who was hungry to participate and capable of doing considerably better than his party. In other words he had the potential to lift the ailing party brand and help kick-start whatever comeback was possible.

But instead of giving him his head back at the start of the summer, Michael Martin dithered. First he tried to pull an old-fashioned political stroke by inveigling Gay Byrne into the race, behind the backs of his own people. And when that didn’t work he simply lost his way entirely. And in the process he opened the door to a virtual coup by Sinn Féin.

Whatever Fianna Fáil do now, they are irrelevant. If they decide to give their Oireachtas members a free hand, they will simply add another independent to the race, in the form of David Norris. And while that would undoubtedly be a good thing for politics generally, it will serve no purpose whatever in terms of the growth and recovery of the party.

Fianna Fáil, despite its drubbing in the general election, still won 387,358 votes. That was the base on which they hoped to rebuild. They have now put every one of those votes at the disposal of Martin McGuinness and Sinn Féin. The Sinn Féin core strategy in this election, right now, is to after each and every one of those votes. And if they win them, they intend to hold on to them.

For a number of elections now Sinn Féin has been looking for a way in to mainstream Irish politics. Their vote has been growing, although incrementally – the recent general election was a 3% improvement on 2007, which in turn was a 3% improvement on 2002. But they have always flattered to deceive, never quite living up to the opinion poll billing they got in the run-up to general elections. In fact, given the bounce they got from Pearse Doherty’s victory in the Donegal by-election, and the dire economic state of the country, their result earlier this year was something of a disappointment for them.

Fianna Fáil’s collapse, of course, did mean that Sinn Féin, for the first time, were enabled to occupy a really prominent position on the opposition benches, with guaranteed speaking time and opportunities to harass the Taoiseach and the Government. They have signally failed to make the most of that opportunity so far, and their parliamentary performance has been weak. All told, one could be forgiven for thinking that Sinn Féin had reached the glass ceiling, and that there was no reason to believe they could significantly improve beyond where they are now.

At a stroke, all that has changed. They have now been enabled to go out and campaign for Fianna Fáil’s nearly 400,000 votes, on top of the more than 200,000 they won themselves in the general election. If they get half of the Fianna Fáil votes now going a-begging, they will double the size of their base. And that will move FF beyond the beginning of the end. There may well be no way back for the greatest political movement this country has ever seen.

Right now, the Presidential election is delicately poised. There was a robust opinion poll in this weekend’s Sunday Independent, weakened only by the fact that opinion was sampled before Sinn Féin pounced on Fianna Fáil’s weakness.

That poll shows the election is finely balanced between the political parties and the independents. Fine Gael and Labour have about half of all the votes available, with Michael D Higgins using his experience to great effect, and occupying pole position. A good transfer pattern between the two government parties, on his present showing, would be more than enough to elect President Michael D.

On the other hand, the three independents accounted for in the poll also have half the votes. Although there is a more even split, the poll clearly shows that Mary Davis is beginning to gather momentum, and if those trends were maintained, she clearly has the potential to break out of the pack. There is still, clearly, a mood amongst a significant proportion of the electorate that doesn’t favour the candidates from “the establishment”, and if Mary Davis becomes the champion of that mood she could end up giving even Michael D a run for his money.

What effect will Martin McGuinness have on all that? Will he inspire an anti-establishment vote or be a damp squib? Will he encourage people to vote in this election who tend not to vote at all – and if they come out, where will their transfers go?

It’s too soon to be certain of the answers to those questions. But it’s already clear that there will be one big loser in this election. I never thought I’d see the day when a presidential election could spell doom for Fianna Fáil. But the sound of nails being hammered into political coffins is getting louder by the day.