The shadow chancellor, Ed Balls, told the Independent this week that it would be "in the national interest" for senior Lib Dems – but not their leader, Nick Clegg – to form a coalition with Labour, and set up a new government without a general election. You'd imagine Balls would have learned, after Gordon Brown failed to go to the country after taking over as prime minister, that the electorate is not keen on politicians bypassing what little they have by way of democratic mandate. But apparently not. Politicians, almost by definition, think that the national interest always coincides spookily with their own interest. It's why they think that they should be in charge.

Technically, such a change of government could be achieved. There is much speculation about David Cameron calling a March election while he is leading the polls, gambling on gaining a Conservative majority. But this, in reality, is out of the question. In virtually their only politically astute move, the Lib Dems insisted, as part of the coalition agreement, on five-year, fixed-term governments. An incumbent prime minister can no longer call an election at the time he thinks will suit him best. This means, right now, that the support of the Lib Dems is more of a hindrance to the Conservatives than a help. Conversely, until such time as Labour can win an election, the Lib Dems serve Labour best exactly where they are.

The political stalemate in Britain at the moment is incredible. This state of affairs cannot continue for another three-and-a-half years. Yet, currently only one party has any real interest in disturbing the deadlock, and that is the Conservatives. Balls may imagine a midterm reconfiguration is possible if Labour gains byelection seats. But actually, there would not be much appetite for standing by and watching Ed Miliband becoming prime minister by default. This would be true even if Labour seemed to be bursting with great ideas for national renewal. But if they were, then Labour, not the Conservatives, would be keen to have an election, the Lib Dems would not be quite so stuck, and talk of back-room deals would be out. Even Balls can't believe what he is saying, not really.

Not that senior Lib Dems would give up their cabinet positions to anoint Miliband anyway, any more than Balls would stand aside to accommodate them in the shadow cabinet. Despite everything – including the way the chief secretary to the treasury, Danny Alexander, and the business secretary, Vince Cable, are used as a human shield to protect Osborne from media appearances – they obviously enjoy their power. Anyway, the Lib Dem sojourn with the Conservatives has already done much to strengthen the first-past-the-post status quo they exist in large part to challenge. A switch to Labour would shore up that wretched binary system even more.

The Lib Dems themselves may as well simply disband, join Labour or the Conservatives, and have done with it, if they are going to start crossing the floor. It would be the end of their party. They know that. It is why they haven't started doing it … yet. The Lib Dems are going to have to do something at some point before three-and-a-half long years are up if their party is to have a chance of surviving beyond their brief moment of coalition glory. Yet they are just as stymied as the other two parties. Cameron's bounce in the polls is because he flounced out of a European treaty meeting; one that was itself all about politics, and pretty irrelevant to the matter in hand, the continuing eurozone crisis. But, the Lib Dems are ardent supporters of Europe. So this thing that the electorate likes so much about Cameron, one can only assume, is something they particularly dislike about the Lib Dems. There may at last be some clear blue water between the Conservatives and their coalition partners. But the tidal currents favour only the Conservatives. As ever, the most the Lib Dems can manage as a check on Conservative instincts is a bit of grumbling – but not too much. Anything else would be principled self-immolation. They've tried that one already. Sort of.

The admiration the Lib Dems imagined might accrue to them because of their noble self-sacrifice has not been forthcoming. Of course it hasn't. It was always a logical impossibility. They gained power from the move into coalition, so there was no noble self-sacrifice to admire. Instead, they look like a party whose leaders were happy enough to wallow in "the old politics", but who just were not very good at it, selling themselves at too cheap a price, and not only damaging, but actually neutering, one of their raisons d'etre – electoral reform. Mind you, the many voices still raised in anger at how the Lib Dems split the left-leaning vote is testament to how Labour's supporters, no less than the Tories, cling to dualistic politics, and the deadening simplicity of an imagined, impossible either/or world.

The only real option open to the Lib Dems is to move into a confidence-and-supply arrangement, as many of their left-leaning supporters had wanted in the first place. Again, this would mean giving back those government jobs. But at least some real self-sacrifice would finally be apparent. However, having been so enthusiastic about so much Tory policy, the Lib Dem problem now is finding a cause powerful and deliverable enough to justify such a stand. If the Lib Dems could come up with more than a sentimental attachment to the idea of the European Community as a reason for opposing the Conservatives on principle, then that would be fine. Yet they seem no closer to offering political solutions than their Europhile friends over the channel. Even countries that are manifestly pro-Europe, with nothing like the ambivalence that has always been present in Britain, find that such ideas are in short supply. The nearest Clegg has got to opposing Cameron was in his ridicule of tax breaks for married couples. But this is a minor irritant in a political culture that constantly seeks to find behavioural levers within systems, rather than genuinely fresh ways of interpreting human psychology. It was more of a lovers' tiff than a political stand. Cable's marriage of convenience has turned out to be convenient only if you enjoy seeing political plurality grinding to a halt, and the "old politics", unfit for purpose as they are, growing stronger and more indefatigable in adversity. It's an ugly, depressing sight.