Usually, by-elections don't matter that much outside their constituencies. Usually they are caused by the death of a TD. Usually they don't have the potential to bring down a successful government. Usually by-elections are politically insignificant, mainly because they rarely reflect voters' behaviour during general elections.
Usually, but not this time.
Right now the Taoiseach is holding together a Government consisting of Fianna Fail and the Progressive Democrats and a trio of "independent" TDs. He is making a good job of it, but that would be unsurprising to those who know him.
He has a remarkable capacity to avoid conflict. But the outcome in Dublin North and Limerick East may take the situation out of his hands. Should both seats go to the Opposition, they will have, potentially, 83 seats as against the 82 FF/PD seats and the Three Amigos.
With the margins that small, an election could be caused by forcing a vote when two or three TDs are absent. The Opposition probably won't, at least not right away. The Government is doing very well in opinion polls at the moment.
However, a little careful application of the Opposition's voting power could hamstring the Government, make it look ineffective and destroy its popularity.
An election in a year or so would have a far greater chance of success. And the parties would be more likely to be able to pay for it. It isn't that long since the last general election, not forgetting the presidential election, and they are expensive affairs.
Should the Government, in the shape of Fianna Fail, take both seats, it would be a huge boost and a major personal triumph for the Taoiseach. The Government's position would be far stronger and the bargaining position of the "independents" would be substantially weakened.
Should only one seat go to the Government, the equilibrium will be maintained.
By-elections are notoriously difficult to predict, and even more so when they are brought about by the resignation of a senior politician and minister as apposed to an unexpected death.
Dublin North will ultimately pit a well-known Labour candidate who lost his seat in the last election and for whom there is a lot of sympathy against a Fianna Fail candidate not well known and located, from the party's point of view, at the wrong end of the constituency.
Yes, there are other candidates, lots of them. Possibly the only typical factor with this by-election will be the number of candidates and, in particular, the number of single-issue runners. Their transfers will be important, and difficult to predict, but in the final analysis only two candidates have a realistic chance of winning.
The Fianna Fail candidate, Michael Kennedy, is based, geographically, quite close to the sitting party TD. That won't affect his chances too badly this time but may prove problematic in any later elections. His best chance of winning is based on the reactions Fianna Fail canvassers are getting on the doorsteps. Unsurprisingly, local issues are cropping up for the most part.
But the major plus - and it is a huge one - is Bertie Ahern. He is popular and the people want to vote for him. Fianna Fail needs to and has started to sell the ideas of good government, stability and Bertie Ahern. He will have to devote a lot of time to appearances in the constituency with the candidate.
It would be tempting to expect a large number of the people who voted for Ray Burke to support Michael Kennedy. Such an assumption would ignore the fact that a lot of Burke's supporters liked him personally and voted for him because he delivered the goods while in cabinet. Michael Kennedy has no such track record and is associated with Burke only through a shared political party.
The Dublin North seat is certainly winnable by Fianna Fail if time and personnel are allocated to it. Limerick East will be more difficult.
One of the key problems there is that a defeat in both elections would raise the prospect of a general election in no more than a year or so. That tends to cause sitting politicians to get very nervous about their seats and can lead to less-than-altruistic behaviour.
Sandra Marsh, the Fianna Fail candidate, is a bright, articulate, personable and capable woman. Though not yet a national figure, she is well known in the constituency through her work in Aer Lingus and her involvement with the Limerick county board of the GAA. Any difficulties she has will not be of her own creation.
The behaviour of Willie O'Dea, one of the two Fianna Fail TDs in Limerick East, is far more problematic. First, he has threatened to sue a local cumann member. To do this to a member of your own party - a member within your constituency no less - at any time would be highly questionable. To threaten to do so in the run-up to a pivotal by-election in that same constituency beggars belief.
Second, in a by-election like this the sitting Fianna Fail TD has an opportunity to influence the result by working hard for the party candidate. My former colleagues canvassing in that constituency tell me there has been little evidence so far of that sort of effort being put in by Willie O'Dea. It may be that he is working assiduously on behalf of his colleague, but that is not the information that is reaching me.
But no better man than Willie O'Dea to know which side his bread is buttered on. If Sandra Marsh were to lose the election by a narrow margin and if even some of the blame for that loss were to be attributed to a sitting TD not putting his weight behind her the party leadership would show no mercy.
As I said, predicting by-elections is a tricky business. But if you feel like having a bet on the outcome and you can get decent odds on a one-one draw you could do worse than have a small flutter.
Should things go badly for the Government we are liable to wake up some morning in the coming 12 months to find we are faced with a general election that few people want.