Perhaps we should have seen it all along. With two candidates from the North, and three from the South, Northern Ireland was always going to figure highly among the issues to be debated.
But now "the National Question" is becoming the defining issue in this election. And the specific form it is taking is this: Is Mary McAleese, as a Northerner, and as a nationalist, a suitable person to become the next president of the Republic of Ireland?
And who better to slug this one out than the Civil War parties, Fianna Fail and Fine Gael? The presidential election has effectively become a two-horse race between McAleese and Mary Banotti, "the fourth green field" versus "the just society".
It's as though the Robinson era didn't exist. The minor candidates are there to make up the numbers and pass on their transfers to the big guns. And all the better for the two main parties if their mutual antagonism keeps internal dissent under control.
This was the week the election campaign finally converged with the political bad blood spilling about in Leinster House. Fianna Fail, sensing McAleese's lead to be under threat, has gone on the offensive.
It claims Fine Gael is orchestrating a campaign to undermine the Government candidate, starting with Banotti's remark on Questions and Answers the previous week that Fianna Fail "had to go to the North" to find a candidate.
But the cat was really set among the pigeons last weekend when the Sunday Business Post leaked a Department of Foreign Affairs memorandum on McAleese. Written by a senior Department official, this appeared to show that McAleese was sympathetic to Sinn Fein.
Since then, events have unfolded at a dizzying pace. On Monday the independent candidate, Derek Nally, challenged McAleese on the memo.
She was working to a "different moral agenda" than most people in the Republic, he claimed. He questioned whether she was a "proper person" to be president.
Nally was acting on the advice of his publicity director, John Caden. He, in turn, was consulting with his friend, the media commentator and "bogyman" of Fianna Fail, Mr Eoghan Harris.
Within a day, Mr Nally was in a tangle. At a debate in Trinity College, he accepted Ms McAleese's word that she had no Sinn Fein links. But the following morning, in an article in The Irish Times, Mr Caden directly contradicted this.
At first, Mr Nally said he accepted Mr Caden's analysis, thereby contradicting himself. But the following day he reversed his position once again. Mr Caden had to go; he resigned early on Thursday morning.
Mr Nally, already struggling after a late start and a poor initial showing in the polls, was made to look the amateur that many suspected he was. Worse still, his image as a gentleman with old-fashioned values was badly tarnished; he has yet to apologise to Ms McAleese for his accusations.
But this was the start, not the end, of the affair. Fine Gael had originally avoided comment on the Department memo. But when the Sinn Fein leader, Gerry Adams, said Ms McAleese was his preferred candidate, John Bruton was off the leash.
The Fine Gael leader described Mr Adams's comments as a "calculated endorsement". It would "render impotent" the role of the president as a symbol of reconciliation if Ms McAleese were elected.
Mr Bruton's attack is designed to lure the 20 per cent of Fine Gael voters who say they support Ms McAleese back to their natural home. It's a high-risk strategy which could backfire.
With Leinster House buzzing with rumours that tomorrow's papers will carry further articles linking Ms McAleese to Sinn Fein, Fianna Fail staged a pre-emptive strike.
Yesterday the party claimed Fine Gael was taking advice from Eoghan Harris, basing its argument on the fact that Harris and Bruton were seen lunching together in a restaurant near the Dail last week. It also called on Bruton to give an assurance that he was not behind the leak of the Department memo, and pooh-poohed his denials when they came.
Mr Harris, who on Thursday described Ms McAleese as a "tribal time bomb", is known to have offered his services to several of the candidates running against the Government candidate.
In the build-up to last night's Late Late Show debate between the five candidates, strategists in both Fianna Fail and Fine Gael were trying to draw their rival candidates into the controversy.
It's not clear what effect this bewilderingly complex dispute will have outside political circles. It was clear even before Ms McAleese ran, when John Hume was mooted as an agreed candidate, that considerable antagonism exists towards Northern candidates.
Wednesday's Irish Times/MRBI poll showed only one major change on the previous one, the continuing slide in the popularity of Adi Roche. As a result, Roche's backers in the left-wing parties have decided to concentrate more on Dublin and the traditional left-wing vote. Their dreams of victory have evaporated, it seems, to be replaced by anxious hopes of a respectable showing.
Although the poll shows McAleese eight points ahead of Banotti, the volatility of voters is greater than ever. The amount of cross-party support is unprecedented, and the number of "undecided" voters continues to swell.
At present, McAleese is poised to pick up more transfers than her Fine Gael rival, but this could change if the television debates prove decisive.
Dana received widespread sympathy after she was mauled by Vincent Browne on his radio programme last week. But in spite of Browne's subsequent apology and her own campaign launch during the week, she seems to be travelling in a different gear to the other candidates.
Her repeated claims of being victimised by liberal media have been enthusiastically received by a minority, but have been otherwise ignored. So her main hope of improving her current 7 per cent support level rests on a good performance in the television debates.
Mary Banotti, fully recovered from the road accident in which she was involved, has toured the country energetically. But her success so far in avoiding the wider political controversies is likely to come under strain, as Fianna Fail gets her in its sights.
John Caden became the first scalp of the campaign this week. But with the battle lines so clearly drawn for the next fortnight, he might not be the last casualty.