It was a small consolation. When the coalition was formed last year, Labour comforted itself with the prospect of a monopoly on opposition. No one doubted that winning back public affection would be hard, but with Nick Clegg's party complicit with the Conservatives, there would be no rival to mount principled attacks on the government. So it seemed. In fact, politics today is defined by a noisy competition to be the leading voice of righteous indignation. And Labour isn't winning.

Coalition has fundamentally changed the nature of political opposition. After a failed experiment in seamless integration with the Tories, the Liberal Democrats are now pursuing a strategy of deliberate "differentiation". That requires the controlled advertisement of disputes within the government and the presentation of Clegg as a moderating influence.

There isn't much evidence that voters are impressed by this approach or that they have noticed it. But Clegg's raids on the larder of opposition have definitely starved Labour of publicity. The battle over the government's health reforms, for example, has been framed by the media in terms of a radical Tory proposal deformed by truculent Lib Dems. Labour are cast as fretful, knuckle-chewing spectators.

Something similar is happening with the debate about Europe. The full spectrum of opinion on Britain's membership of the European Union is contained within the coalition, which reduces the significance of Labour opinion.

Unloved Tories

Disagreement between Clegg and David Cameron over Europe is not, like some coalition "rows", choreographed. It is, however, managed with civility born of a shared interest in keeping the government stable. That collegiality alone is enough to keep rebellious Tory backbenchers fuming.

Some of the 81 Conservative MPs who defied the Prime Minister to vote for a referendum on EU membership on 24 October did so through single-minded hatred of Brussels. Many more were animated by broader alienation from the Cameron project, indignation at the high-handed methods used to whip them into line, and a feeling that the government is not truly Conservative and so not deserving of the usual loyalty. "A lot of it was people feeling generally unloved," says one Tory MP. A senior government adviser puts it differently: "The roots of Cameronism don't run that deep in the party."

The combination of angsty Lib Dems and resentful Tories means there are a lot of MPs on the government benches who feel licensed to indulge opposition tendencies. Across the House, Labour struggles to shed the habits of dull caution acquired in government. The party is torn between the urge to capitalise on public anger as the economy sours and fear of surrendering credibility as a responsible party of power. One senior shadow cabinet minister describes the party as feeling "marooned between government and opposition".

Much of the discussion in Ed Miliband's inner circle over the past year has been about reviving something heroic called the "Labour tradition", which is all about community activism and working-class solidarity. That is quite a leap, given voters' feelings - expressed in private polling after the last election - about who Labour stands for. The short answer, summarised by a leading party strategist, was "immigrants, scroungers, bankers".

That view is shifting. The Labour front bench is increasingly optimistic that it can win back an audience on the economy. There is quiet confidence, bolstered by focus groups, that the distinction between "predatory" and "productive" kinds of capitalism, outlined in Ed Miliband's party conference speech, resonates with voters. Some Tories privately agree, having piled public scorn on the idea.

One of Miliband's biggest problems is keeping ownership of the insight. His emphasis on "the squeezed middle" was also once derided, shortly before it entered the everyday political lexicon. "But Ed doesn't get the credit for it," laments a shadow cabinet minister.

A large part of the problem is the proximity of Labour's legacy in government. Miliband wants to represent a bold alternative to the established order, but memories are too strong of his party's role in establishing that order. Meanwhile, more dynamic challenges are cropping up elsewhere. The occupation at St Paul's by a meagre band of protesters has spurred the Church of England into something approaching moral panic. The parliamentary vote on an EU referendum that so disturbed Tory equilibrium was triggered by an online petition. Another e-campaign, calling for tougher government action on immigration, is gathering momentum. One shadow minister recently complained to me that 38 Degrees, the web-based group whose "Save the Forest" campaign forced a government U-turn on woodland privatisation, was a more effective foil to the Tories than the Labour Party.

Deeper malaise

That gripe is symptomatic of a deeper malaise in parliament. MPs on all sides are despondent, worried about irrelevance, sensing that real politics is happening elsewhere. Westminster is in a crisis of popular representation. On the right, this manifests itself in a fetishistic attachment to the idea of referendums, bypassing parliament to join in popular congress with the nation. On the left, there is an equivalent romantic affection for mass protest - the supposed amplification of moral authority by a show of numbers in the street.

This demotion of representative politics is a problem for all parties, but Labour feels it most acutely. Denied access to the levers of government, Miliband's team is reliant on the creaky procedures of parliament to get its points across and even in the Commons chamber they compete with rebellious Tories and Lib Dems to be the sharpest thorns in the PM's side. Political anger is on the rise in a culture that has long been anti-politician. Far from enjoying a monopolistic right to take on the government, Labour risks being drowned out in a cacophony of outrage. Opposition is everywhere but there is no clear reason why it must rally to a man in parliament who happens to be called, by convention, "leader of the opposition".

Rafael Behr is chief political commentator of the New Statesman