The crisis of Peter and Iris Robinson, falling hard upon the heels of the fall of the House of Paisley, may well mark the end of dynasty politics in Northern Ireland. But its significance is far greater than that.
The first minister, Peter Robinson, was the Irish and British governments' best hope to achieve delivery of the final critical stage in the peace process -- the devolution of policing and justice powers to Northern Ireland.
Wounded as he now is, even if he manages to maintain his leadership in the short term, has he the capacity to persuade the increasingly assertive right wing of his party to cut the final deal with Sinn Fein? The problem is that Sinn Fein has it in its power to retaliate by bringing about a crisis of the institutions that may be fatal to the whole process.
Since long before the electoral eclipse of David Trimble in 2004, Mr Robinson was the favoured politician of those not only in the Northern Ireland Office but in the Department of Foreign Affairs and the US State Department. Such mandarins regarded David Trimble's Ulster Unionist Party as dysfunctional. Their problem is that now Peter Robinson's DUP looks even more dysfunctional.
The cool, calculating Mr Robinson appeared to officialdom as the man who could deliver. Many of the issues that have led to the current scandal engulfing the Robinson family may well have been pretty well known inside government. But the decision was made to rely on Mr Robinson as much as possible. It is not difficult to see why.
In the past few weeks, as first minister he seemed to give off the signal that he might, in the right circumstances, be capable of negotiating the next step with Sinn Fein. But the truth is that, even before this crisis broke, his position was weakening. His personal poll ratings were weak.
The brutal fact is that we were heading for a dangerous political crisis in Northern Ireland even before the Robinson revelations. It is now very difficult indeed to see how it might be avoided. Of course, Sinn Fein could show forbearance. It could take the view that this latest development is an act of God that inevitably will take the DUP some weeks to sort out, and that therefore more time should be allowed for political negotiations.
The problem here is that Sinn Fein believes that it has had an implicit understanding that there would be rapid devolution of policing and justice powers away from London to Northern Ireland since the St Andrew's Agreement of 2006 and that in each succeeding year it has been subjected to foot-dragging. This in turn makes it look weak in their own community and helps the rise of the dissidents, who launched a murderous attack on yet another Catholic policeman last week.
While the British government is inclined to believe that Sinn Fein's tactics and rhetoric are at least partly to blame for the fact that Mr Robinson did not have the space to deliver when he was strong enough, it nonetheless takes the view that the devolution of policing and justice is essential to stabilise the institutions and marginalise the dissidents.
The problem is that large swathes of the unionist community view matters entirely differently. They regard devolution in this sensitive area as likely to have little good effect on security policy in the face of dissident activity. In parts of the unionist right wing it is genuinely believed that they are faced with a nightmarish scenario in which republicans are in government with an influence on security policy while other republicans pursue violence in the streets.
This is to ignore the reality of the split in the republican movement. But nonetheless a significant number of unionists in Northern Ireland are inclined to take the pessimistic view of these issues. This is why the DUP chief whip, Lord Morrow, has openly stated that there will be no devolution of policing and justice before the next general election and that, consequently, Sinn Fein has to accept another delay.
There is little likelihood that Sinn Fein can accept this quietly, even though it may well be the best way for devolution to take place before the end of the year. It should not be forgotten that Gerry Adams is also embroiled in an embarrassing controversy, over child abuse, in his own family. Sinn Fein might well feel it is better to keep the focus on the DUP's political failures.
Sinn Fein has the capacity to bring down the local power-sharing executive and to ensure that any election in the near future will be held in the most chaotic circumstances. There is even the realistic possibility that Sinn Fein might emerge then as the largest single party and have the right to the position of first minister -- something that is likely to be unacceptable to even pro-Agreement sentiment among the unionist community.
In the era when David Trimble was first minister (1998-2003) there were two such collapses of the institutions occasioned by this political-ethnic stand-off. Then the Blair government (once in defiance of the Clinton White House) suspended the institutions and allowed a cooling-off period of several months to allow re-negotiations that then moved things along.
More recently, however, the British government, under Sinn Fein pressure, stripped itself of the power to suspend. This means that we could now face a very hard landing indeed. There is still majority support in both communities for the power-sharing institutions but in the complex crisis that is unfolding it is not immediately obvious how that reality can express itself.
Paul Bew is professor of Irish politics at Queen's University, Belfast