The statistical difference between 100 days and eternity is easy enough to establish.

In the weeks, days and hours remaining until polling, however, you might be forgiven for losing track. From now until 7 May, every day is Groundhog Day.

Of pet theories there will be no shortage; of facts, a dearth. My home-made suspicion is that uncertainty will take us, as the sports folk like to say, down to the wire. We already know all the important facts. What remains to be seen is whether a ton of money and incessant chatter can alter reality in the long days ahead.

Here's one fact: parties we used to call mainstream are, by any historical standard, remarkably unpopular. Their leaders are not - let's say - well-regarded. Their pitches are tediously familiar, their tactics from another age. What were once known as traditional loyalties are as soft as wet pastry. Established politics is in trouble.

Hence another fact. What used to be called unprecedented in the political tradecraft of an imperfectly United Kingdom has become, within fewer than five years, common coin. Sky News does a poll of polls and reports what most guessed: a hung parliament come May. Labour will, on this reading, swap places with the 2010 Tories as largest party and twist itself into knots for the semblance of power.

Until recently, this was not the British habit. This was not how things were "done". First-past-the-post used to be Westminster's insurance against multiplicity and chaos. It kept two factions and a Jiminy Cricket party in posturing rights and both big teams - though perish the thought - liked it that way. First-past-the-dinner-gong ensured "stability" in government.

In 2010, things began to break apart. Back then, no one believed that an ad hoc coalition could last. Forget those "profound philosophical differences" between Tory and Lib Dem: divvying up the jobs became one of the chief issues of the emergent administration. In 2010, all believed that someone would puff at the house of cards and bring it down. The fact that the coalition has held together speaks volumes about decadence and self-interest.

Now we discover that the British system does not abhor back-room deals in smoke-free rooms. First-past-the-next-contender-for-ermine has proved flimsy, as a voting system, in keeping picturesque minorities at bay. Voters have chanced upon a novelty: if you cast a ballot for things you actually believe, remarkable consequences can ensue. At the very least, you can give some people a hell of a fright.

To say the familiar parties are not coping well isn't saying much. Among Scots, a generation ahead of their UK peers in voting sophistication, the news from yesterday is as much a test of credulity as any dumb TV quiz. Vote SNP and you'll wake up to the Tories; vote SNP and you'll put Labour in. Really? So, in terms of lived experience, what? Those inclined to support Green, Plaid, or even - if their wits have taken a day off - Ukip, are being treated to the same racket elsewhere in the kingdom. Who believes it?

If nothing else, it misses the point. Some of those putting out all the noise no doubt persuade themselves that what worked in Scotland's referendum can work again. They forget to ask, first, what really went on among the Scots in September; secondly, why the parties from whom they draw wages should be held in such deep and utter contempt. Negative campaigning was born of American presidential struggles: it runs out of road after a generation.

As we reported yesterday, the UK's choice of a Westminster government is too close for anyone to call. Sky's slightly-fantastical averaging of putative average swings should not be anyone's guide for 8 May, but all the evidence this January points to trouble for those who believe that the UK needs and must have a Westminster duopoly. This is fundamental democracy: the people don't want it.

In large, crushing numbers they do not seek to make Ed Miliband Prime Minister. By a marginally smaller degree, they are not enthused by David Cameron. What are those polling numbers? That a Tory leader is better trusted, 29 per cent to 28, to maintain the NHS than the man in charge of the party that founded a British institution? Perhaps we should look instead at the sheer distrust earned by each individual. On this election issue, we don't rate them.

We are supposed to believe, nevertheless, that one or the other will be running the country in May. Punditry has not reached the outer limits of a limited imagination. It suspects confidence and supply deals under a minority government. It wonders about another election, as in 1974, to "settle matters" and "provide stability". In this, all those self-styled radical thinkers fail to think too hard.

The Fixed-term Parliaments Act 2011 was the coalition's attempt to subvert all the constitutional doctrine that has made Westminster so entertaining for so long. If push comes to shove this summer, it will be cast aside in an afternoon. The "big party" likely to believe it can win at a second election will try to shout down the objections of the party worried about losing. But why should the rag-tag rest, if they hold the balance of power, play along?

There's the stable government argument, of course. We have endured an administration dedicated to one version of stability for close to five years. It has not been markedly popular. So if there is a hung parliament in May, why would the newer, smaller, regional, and allegedly novel parties want to help the duopoly out of an impasse?

Voters who will not be bullied in May need to think about these things. Contempt for the old lags will not, of itself, give the UK a government that begins to reflect the diversity of opinion. Let's say you admire the coalition. Does that mean you would prop them up until David Cameron and Nick Clegg can take a third crack at actually winning majority support from the electorate? You might do better - just a suggestion - to keep them as an eager-to-please minority government.

The same would apply, of course, to anyone who has sympathy for Mr Miliband, or for the SNP and the opportunities before it, or for the Greens, Plaid, or the parties of Northern Ireland. The big voodoo in British politics is that there "must" - because it's a rule - be fixed, stable and unquestioned government for half a decade at a time. Why?

Since most things in the UK are a mess, why should Westminster be exempt? Scotland's "decisive" referendum has turned out to be no such thing. In fact, its aftermath has become one of the main contributory facts to our season of General Election uncertainty. That was probably inevitable. It certainly does not count as a coincidence or a tragedy.

A government that has to make its peace week by week with those who represent political realities in the UK would not count as a bad thing. It would resemble the representative government of which we hear so much. It might encourage people to believe votes matter. And it might just bring the House down.