Nick Thornsby: As a Liberal Democrat, I ask - What are you, our Coalition partners, playing at?

Nick Thornsby is one of the editors of Liberal Democrat Voice. Follow Nick on Twitter.

When Parliamentary arithmetic forced the Conservatives and Liberal Democrats to govern together in May 2010, many had cause to be concerned. First past the post had done its job of delivering Commons majorities for decades; the UK was more used to party leaders insulting each other from their dispatch boxes than sitting around a table thrashing out compromise.

More concerning still, the junior party in the arrangement had never seen power. Not a single Liberal Democrat MP had had the privilege of carrying a red box. How, wondered the civil servants whose job it is to be concerned about such things, would the party cope, putting aside the easy indiscipline of opposition to actually make decisions at a time of national economic crisis?

Three years in and those fears look to have been misplaced, in the true sense of the word. For it is not the the junior party that is cracking under the strain of government, but the Conservatives. The party of Winston Churchill, governing at a time of challenges not equalled since that leader, has been thrown into a tailspin by a mustard-trousered maverick who has taken to touring the country doling out shallow populism to apathetic voters.

That many Conservatives themselves had not seen power for over a decade is no doubt part of the explanation, with MPs forgetting some of the basic rules of politics: governing is tough, mid-term results are always bad, when living standards suffer expect your party to suffer too. So the (actually relatively small) Basil Fawlty contingent of the Parliamentary Conservative Party has seized the moment, hijacking an agenda with potentially wide electoral appeal to clog up Parliament and the airwaves with interminable discussions about their favourite subject of Europe.

It is clear to everyone looking in from the outside that if the Tory Party does not get over itself sharpish, historians will look back at this as the moment the party destined itself to spend another decade, or longer, on the opposition benches. But the actions of Conservative MPs, and the reaction of their leader, are not only making that elusive Parliamentary majority -- already looking increasingly distant -- unattainable, they are also, in two crucial ways, jeopardising any hope of returning a Conservative to Downing Street as part of a future coalition.

First, backbench Tories are pushing the party further away from the centre ground from where not only are elections won, but coalitions made possible. Given that, even on the most optimistic projections for Ukip and most pessimistic for the Liberal Democrats, it will be the still be the yellow party and not the purple one that will hold the balance of power in a 2015 hung parliament, every move rightwards by the Conservatives pushes Nick Clegg closer to Eds Miliband and (most worryingly) Balls.

In following the Peter Bones of the party, who think governing without a majority or even staying in opposition is preferable to a coalition in which their party occupies 10 and 11 Downing Street and 17 out of 22 Cabinet positions, Tory MPs are in danger of losing touch with reality, and replacing influence with impotence.

Secondly, and more significantly, is the Prime Minister’s failure of leadership, which has already caused the most serious crises of the coalition to date. The first occasion was the AV referendum. In choosing to side with some of the most reactionary voices in British politics -- Tory and Labour -- and authorising attacks on his deputy in the process, the Prime Minister killed the coalition’s early reformist zeal in an instant, while defeating reforms which would have contributed to the long-term success of Project Cameron.

Then, in failing to even attempt to deliver his party to reform the House of Lords, he once again put short-term party management ahead of long-term strategy. And, predictably enough, he lost the one reform -- of constituency boundaries -- that would have done more than anything else to make a majority possible in 2015. These failures to follow his better instincts, bowing instead to pressure from the very people who now threaten the core of his agenda, leave the Prime Minister almost totally stripped of authority.

And if a party leader cannot persuade his party to implement even the agenda on which they were elected, what chance that he can persuade them to sacrifice some of that agenda and replace it with another party’s? That guarantee is a fundamental prerequisite to coalition, and it is one that David Cameron looks increasingly unable to meet.

As a Liberal Democrat who regrets the passing of the coalition’s early radicalism, and who had hoped that David Cameron and those around him could govern as modern, moderate, sensible Conservatives, this regression is disappointing. But for Conservatives who are more interested in achieving things than in bombast over Europe and equal marriage, it should be more than disappointing. We are witnessing the slow demise of moderate conservatism in the Conservative Party; the replacement of broad electoral appeal with narrow, pessimistic, Europe-obsessed nationalism. And all because government is proving a bit too difficult.

The chances of that programme leading to electoral success are non-existent; the chances of another party wanting to work with such a party are only slightly higher. Unless the Prime Minister starts to show some leadership, he will secure his place in history as a one-term leader of the country. And unless Conservatives get behind him they will return once again to the powerlessness of opposition, where they can bang on about Europe until they’re blue -- or purple -- in the face.