Ed Miliband photographed for the New Statesman in 2012. Photo: Kate Peters/New Statesman

No British election since 1979 has been as momentous as that which will be held on 7 May. The United Kingdom’s continued EU membership, the size and purpose of the state and the survival of the British Union are all at stake. The end of the long era of political and economic stability that followed the 1997 election, in which Labour returned to power under Tony Blair, has reanimated arguments once thought settled.

Having served a full term in government, the contention of the Conservatives and the Liberal Democrats is that they deserve to be rewarded for their record, the former by winning their first majority since John Major won more than 14 million votes in 1992 and the latter by acting as a moderating influence in another hung parliament. It is the coalition government’s erratic record, however, that provides the greatest evidence of why they should not be entrusted with power.

The coalition entered office in 2010 determined to eliminate the Budget deficit in one parliament: this was to be our new era of fiscal rectitude. We warned repeatedly that this aim would be imperilled by premature consolidation – and so it proved. The increase in VAT, the deep cuts to infrastructure spending and the hyperbolic and fatuous comparisons made between the UK and Greece all helped to halt, or “choke off”, the recovery that was under way in May 2010. Indeed, Britain endured its worst-ever post-recession performance.

Growth eventually returned and employment rose to a record high of 73.4 per cent but it was too concentrated in low-wage, low-skill sectors. The resultant shortfall in tax revenue forced George Osborne to extend his deficit reduction programme by four years. Yet, far from learning from this error, the Chancellor now proposes to repeat it by promising a Budget surplus by 2018-19 – an ambition that could be achieved only through extreme and almost certainly undeliverable spending cuts.

Through an act of political conjuring, the Tories have transformed economic failure into the appearance of success. However, the financial stability that they trumpet is threatened by their pledge to stage an in/out EU referendum by the end of 2017. This policy, forced on David Cameron by his recalcitrant backbenchers and the UK Independence Party, represents the greatest risk to prosperity, to Britain’s global influence and to the survival of the Union. Were the UK to vote to leave, the Scottish National Party would demand a second independence referendum on the grounds that the state that Scotland chose to remain part of had been fundamentally altered. A rampantly Europhobic Conservative Party, which would find it far easier to win majorities in a rump UK, may now regard this as a price worth paying.

The promise to shield the poorest from the worst of austerity, emblematic of David Cameron’s “compassionate Conservatism”, was not kept. Measures such as the “bedroom tax”, the household benefit cap and the arbitrary use of benefit sanctions have frayed the safety net and contributed to the rise in food bank usage to more than one million. The £12bn of further welfare cuts promised by the Conservatives would inflict much harm on the unemployed, the working poor and the disabled.

Years of privation for some have been accompanied by years of plenty for others. The 50p income tax rate, which the Tories originally suggested they would retain in 2010, was abolished and, even as property values swelled, Mr Cameron rejected a “mansion tax” on the grounds that “our donors would never put up with it”. His party’s promise to eliminate the remainder of the deficit through spending cuts alone would further widen the UK’s already vast inequality.

After entering office, inspired by iconoclastic advisers such as Steve Hilton, the coalition pursued public service reform with absurd haste. The results did not justify the rhetoric. The NHS was subjected to an unpromised and unnecessary reorganisation that squandered £3bn at a time of fiscal restraint. The botched implementation of Iain Duncan Smith’s master plan, Universal Credit, wasted further resources and reduced welfare reform to mere austerity.

Liberal Democrat supporters of the coalition point to achievements such as the introduction of equal marriage, the pupil premium and the fulfilment of the 0.7 per cent foreign aid target. These gains are outweighed by the damage inflicted elsewhere. The Liberal Democrats blocked many of the Conservatives’ worst proposals but they are equally culpable for the government’s failures. Having gifted Mr Cameron the majority he lacked in 2010, they achieved little in power, notably on constitutional reform. Nick Clegg’s clear preference in this campaign for another partnership with the Conservatives, even at the cost of the UK’s EU membership, demonstrates that his party could enable further harm.

Neither of the coalition parties deserves to be returned to government. The Prime Minister boasts that the Tories are now the “party of working people”. Yet absent from his re-election campaign is any sense of moral mission. It is not enough simply to say, as Mr Cameron does, that the country is doing better under him. The people have to feel it and believe it. They do not. The lack of any meaningful swing towards the Tories in the opinion polls reflects this truth. Instead, it is Labour, after a single term in opposition, that has the best chance of entering office, even if only as a minority administration dependent on support from smaller parties.

We endorsed Ed Miliband in the 2010 leadership contest as the candidate most committed to breaking with New Labour and to effecting far-reaching political and economic reform. Mr Miliband has remained true to this vision while keeping his party unified. He has performed well in the election campaign, growing in confidence as a communicator as his personal ratings have improved. But his five years as opposition leader have revealed severe limitations and strategic weaknesses. He has never succeeded in inspiring the electorate and has struggled to define himself. His narrow rhetorical and ideological focus on political economy has left him unable to reach the aspirational voters required to build a broad electoral coalition (see Jason Cowley’s report on Harlow in this week's issue). Finally, even after the SNP’s victory in the 2011 Scottish Parliament election, which we predicted, he remained complacent over Labour’s decline in Scotland, where he is even less popular than David Cameron. It is the surge in support for the SNP, which has positioned itself to the left of Labour, that has definitively ended Mr Miliband’s hopes of winning an absolute majority. Should he become prime minister, he will now almost certainly be reliant on the support of a large nationalist bloc to govern. In such circumstances, perhaps his greatest task as prime minister would be to reimagine British nationhood, if this is even possible, and craft the reconfigured Union that is essential if Scotland is not to break away in the next decade.

A more nimble and agile leader than Mr Miliband would have better exploited the historic opportunity provided by the collapse of support for the Liberal Democrats and the divisions on the right created by the rise of Ukip. The paradox of austerity is that it offers opportunities to be creative and to rethink social democracy in a cold climate. Mr Miliband has not changed the character of his party enough. He has not created a sentiment from which truly transformative policies could have flowed. He argues simultaneously for more austerity and more socialism.

Yet the programme put forward by Labour in this election is still one that is worthy of support. Inequality, the root of so many of the our maladies, would be tackled through a more redistributive tax system, an increase in the National Minimum Wage to £8 and employee representation on company remuneration committees. A more productive and balanced economy would be built through the establishment of a national investment bank, the transformation of vocational education and the devolution of £30bn to city and county regions. The housing crisis would be urgently addressed through the construction of 200,000 homes a year by 2020. (We would also like to see land reform and the introduction of a land value tax.) The deficit would be cut pragmatically, rather than with ideological haste.

The most egregious measures imposed by the coalition, such as the bedroom tax and the Health and Social Care Act, would be repealed. The unelected House of Lords, an embarrassment in a modern democracy, would be replaced with an elected senate of the nations and the regions. And the UK’s EU membership would be safeguarded through the avoidance of an unnecessary referendum, though reform of the EU is necessary. But even those who feel little enthusiasm for this programme ought to consider voting Labour if they wish to evict the Conservatives from office. As a result of our antiquated first-past-the-post system, which we hope will not survive beyond this election, they cannot do so otherwise. We have been cheered by the emergence of our new multiparty democracy but only a reform of the voting system will produce genuine pluralism. In the Labour-Conservative marginals that will determine the result, a vote for the Green Party or other progressive alternatives only aids Mr Cameron, who has been demonising the SNP in recent weeks in a desperate attempt to cling on to power.

Britain is a great country, one of the safest and most prosperous in the world. It has the potential, also, to become a more equal and more democratic country in the next five years. The best means of fulfilling these hopes is to return a Labour government on 7 May.