What if none of them ends up in Number Ten?

Before the current election campaign got under way, there were some pundits who predicted that it could become the first such contest to be decided over the worldwide web.

But apart from one Labour candidate who made a fool of himself by using foul language on Twitter – the twit in question was swiftly forced to quit – talk of an ‘internet election’ has proved wide of the mark.

Instead, it has been the relatively old-fashioned medium of television which has led the way, with the debates between Gordon Brown, David Cameron and Nick Clegg proving to be the pivotal events in the campaign.

Indeed, they have assumed such a degree of significance that much of what has happened in between them has seemed a bit like waiting for the next course to arrive in a restaurant.

After the first debate, I wrote that it was beginning to look as though the will of the public in this election may be to deny both of the two main parties an outright majority.

At the time, it was a somewhat tentative conclusion, but the “Cleggmania” that erupted over subsequent days suggested it wasn’t far off the mark.

If proof was needed that it is the Lib Dem leader who is setting the agenda in this campaign, one need only look at how the second debate on Thursday contrasted with the first.

Whereas in the first one the prevailing attitude of the other two leaders was “I agree with Nick,” in the second one they were finding as much to disagree with him about as possible.

Another thing I wrote last Saturday was that the Lib Dems can expect an onslaught from the 'big two' over the next few days such as they have never seen.

In truth Labour has been rather muted in its criticisms, but the attacks on Mr Clegg in Thursday morning’s Tory-supporting newspapers will have done Mr Cameron’s party little good in my view.

The public has come to see that kind of journalism for what it is – not journalism, in fact, but merely an extension of the yah-boo politics they have come to loathe.

If the Cameron camp was hoping it would burst the Clegg bubble, it is already clear that it has signally failed to do so.

That said, both Mr Cameron and Mr Brown can certainly take heart from this week’s debate, which saw all three contenders much more evenly-matched than the previous one.

Indeed, Mr Brown’s ratings improved so markedly that he might even entertain hopes of coming out on top in the final, surely decisive confrontation this coming Thursday.

The Prime Minister is nothing if not resilient, and his “like me or not” passage in which he tackled his own lack of personal charisma head-on will have gained him a certain amount of respect.

There remains, though, a strong feeling in the electorate that, after 13 years and a record that can best be described as mixed, this government has finally run its course.

For that reason, we can expect to hear Mr Cameron continuing to hammer away at his core message over the next week that only a vote for him can spare us another five years of Mr Brown.

It is not, as it happens, strictly true. The price of a Lib-Lab pact could well be the Prime Minister’s head on a platter, in which case expect to see South Shields MP David Miliband summoned to the Palace.

Of all the possible denouements to this extraordinary campaign, that would surely be the most bizarre – that none of the three contenders who have slogged it out over the airwaves actually ends up in Number Ten.

The fact that such scenarios are even being discussed is a measure of just how unpredictable this whole election has become.