One of the stranger superstitions in modern politics is that bookmakers' odds are more reliable than any opinion poll.

It's strange because, as students of the horses will tell you, close attention to movements in those numbers doesn't often lead to wealth beyond the dreams of Sir Malcolm Rifkind.

Still, if people want to back fond hopes with cash, bookies are happy to oblige. Their problem is that this year neither they nor their customers have the slightest idea of what May 7 will bring. Everyone is stumped. Everyone is waiting, or hoping, for the decisive event that will swing the contest. Of that, there is no sign.

So Paddy Power will give you 4/1 on a Labour minority government. But the firm will also offer 4/1on another Conservative-LibDem coalition. If that's confusing, the odds on a deal - a "coalition", indeed - between Labour and the SNP are currently ... 4/1. With a Conservative minority at 9/2, a Tory majority at 5/1, and a pact between Labour and the LibDems at 13/2, there is, essentially, no favourite.

The only interesting thing in this sport is that Paddy Power and its clientele see less chance of an outright Labour majority (8/1) than of a straight Conservative win. Those are the odds despite the fact that UK Polling Report projects Labour as the largest party, albeit 18 short of an overall majority. The electoral system's generosity towards Ed Miliband's team should also count for something. By a narrow margin, the money says otherwise.

Among the parties likely to lead a Westminster government, uncertainty is causing various degrees of panic for various reasons. You could make a list of the questions. How badly will the SNP damage Labour in Scotland? How much pain can Ukip cause the Tories in the English south and Labour in the north? What can the LibDems salvage from the wreckage? What will be the impact of the Green vote? How will tactical voting play out?

There's plenty more where those came from. At the heart of it all lies the fact that, according to the final YouGov poll of the week, Labour (34 per cent) and the Tories (33 per cent), can barely manage two-thirds of the UK vote between them. In Scotland, things are very much worse for both parties. And both have resorted to campaigning in a purely negative way.

So William Hague, Leader of the House, warns us of the dangers of an "unstable coalition" if Labour ends up in an informal pact with the SNP. So Ruth Davidson, Scottish Tory leader, finds herself quixotically urging Conservatives to vote Conservative while tales circulate of her supporters preparing to clutch their noses and back anyone who might stop a Nationalist. Labour people, sotto voce, are recommending the same course.

In the public arena, meanwhile, all is contradiction and confusion. Vote SNP, says Labour, and you'll let David Cameron back in. Vote Labour, say Tories, and you'll grant power to those SNP wreckers. Throughout it all the Nationalists remain where they were in the days following last September's referendum: with the equivalent (or better) of the plebiscite's Yes vote. What this means for Labour, even without an improbable uniform swing to the SNP, is carnage.

Mr Hague might detect the ironies. Even if all the gods available smile on his Scottish party it won't make much difference to the Westminster tallies. But if Scottish Labour founders and Mr Miliband makes the call to Nicola Sturgeon, Scotland will matter a great deal. So the Leader of the House, though stepping down as an MP, predicts instability and a "leftward drift" for Labour under the SNP's influence.

It's an interesting acknowledgement of where two parties stand politically, but it barely begins to tell the story of post-election deals and where they might lead. Mr Hague fears instability? So what happens if the Tories are able to stitch together another coalition with the LibDems? If the promise of a referendum on Europe by 2017 is kept, any such arrangement will come apart at the seams. Nick Clegg's party has sacrificed a lot for a taste of power, but its opposition to withdrawal from Europe is sacrosanct.

And what of Labour and the SNP? The less-than-loyal Labour Uncut website this week ran some gossip alleging that people "around" Mr Miliband see advantages in an arrangement with the Nationalists. First, they could rid themselves of the troublesome Ed Balls, Shadow Chancellor, with his irritating objections to the leader's tuition fee plans for England and his devotion to austerity. In this incarnation the party, grandly, would "reset its economic standing with the public" - and make itself acceptable to the SNP.

According to the conspiracy theorists, any "rage" exhibited by Jim Murphy at such an outcome would not be unwelcome in Mr Miliband's circle. It sounds like a formula for chaos: ditching a Shadow Chancellor whose wife, Yvette Cooper, happens to command the Home Office brief while humiliating your new, if scarcely trusted, Scottish leader. But if push comes to shove, another calculation might prevail. How many MPs could the SNP offer, and how many could Mr Murphy provide?

Visiting Scotland this week, Mr Balls was in no mood to discuss the Nationalists or their demands. For him, beating the Tories, in the old style, remains the only objective, despite the facts on the ground. Perhaps he believes any other narrative would sound defeatist. Perhaps he was acting on Mr Murphy's advice. But Labour Uncut's tale only echoes the polls and the bookies. If Mr Miliband cannot win outright, what are his choices?

If conventional wisdom was worth a minute of Jack Straw's precious time, Labour would be doing far better. The referendum result would have restored the party in Scotland, for one thing. For another, controversies over the NHS would have propelled Mr Miliband into Downing Street. Scandals over tax evasion would have been a bonus. Nothing has worked. Doubts over the leader's suitability for government, far less his ability to get through a general election campaign, run deep.

Mr Balls is thought to be among those who would settle for minority government rather than submit to the SNP. It's an honourable choice, as far as it goes. The idea that Labour could come to terms with Ulster's Democratic Unionists is a fantasy, not to say irrelevant. Mr Miliband's team dislike the Liberal Democrat team intensely. Besides, LibDems could be thin on the ground on May 8.

But if Labour won't meet Ms Sturgeon's demands over Trident and austerity - Labour voters can wonder where the problem lies - a minority government is all that remains. It might last a year or two, irrespective of the Fixed-term Parliaments Act, before a Miliband administration found itself facing the prospect of another election. That would not be a prospect to relish.

There are other scenarios, lots of them. You can get odds on almost every imaginable permutation. Most of them would have sounded fantastic just a few years ago. But instability, as Mr Hague terms it, is the mark of a kingdom that is anything but united, and of a political establishment for whom mere disrepute would be an improvement.