British politics is being reshaped across the spectrum, and it’s not a pretty sight. You might have imagined, after David Cameron’s election victory, that Labour would use its leadership contest for a genuine debate about how to regain power. After all, the result was as complex as it was unexpected. The Tory 12-seat majority, won on less than 37% of the vote, was nothing like the landslide portrayed. Labour haemorrhaged votes on its left to the SNP and Greens, and on the populist right to Ukip, but won more votes in England than Tony Blair did in 2005.

It failed in small-town England but advanced in London and big cities. It continued to lose working-class votes but bolstered its middle-class support. How to weave together a winning electoral coalition out of such fragmentation is far from straightforward. But you’d never know that from the response of Labour’s leadership candidates. Taking their cue from Blair and a string of former New Labour luminaries, all have fallen in – with more or less enthusiasm – behind a Blairite agenda.

The problem with Ed Miliband’s leadership, they intoned from the start, was that it was “anti-business”, put a “cap on aspiration”, threatened rich people with punitive taxes, and failed to accept that the last Labour government “overspent” in the runup to the crisis of 2007-08. Two of them, Chuka Umunna and Tristram Hunt, have now bowed out. The rest have stuck to the script. Liz Kendall, the most unreconstructed Blairite (or moderniser, as their media backers still insist on calling them), claims the plan to restore the 50% top tax rate was a “major problem”.

Yvette Cooper, while declaring she wants to go “beyond old labels of left and right”, has turned sharply to the right. Miliband’s distinction between corporate “producers” and “predators” had been “anti-business, anti-growth and ultimately anti-worker”, she said, and Labour should support further cuts in corporation tax.

Andy Burnham, portrayed as the union-backed Miliband continuity candidate by much of the media, agreed Miliband’s attacks on predatory capitalism had been a “failure of communication”, its pre-crash deficit had been too high, and Labour’s mansion tax had spoken to “the politics of envy”.

So all Labour’s leadership candidates have decided that the reason the party lost was its support for modest increases in taxes on the wealthy and steps to rein in untrammelled corporate power. But what evidence is there that these policies sank Labour’s campaign? None whatsoever. In fact the mansion tax, 50% top tax rate and privatised energy price freeze were among Labour’s most popular policies. And polling has regularly found large majorities want the government to be “tougher on big business” – as well as an end to austerity.

Labour’s leadership campaign has been led by a Blairite agenda which doesn’t reflect public, let alone Labour, opinion

Turning their backs on tax justice and retreating to the fateful corporate embrace of the Blair years not only puts Labour’s leaders on the wrong side of public opinion and outrage at rising inequality. It even puts them firmly to the right of the prime minister’s former adviser Steve Hilton, who has this week been calling for action against corrupt corporate and elite power.

We already have some sense of why Labour lost the election. Miliband was unable to cut through as a leader, while the party never regained the economic credibility lost in the crash of 2008 – nor discredited the ludicrous claim that overspending caused it. Nor did it win back the trust of working-class voters left behind in the New Labour years. Its policies lacked a clear political framework – and the Tories and their media pack played the SNP card against it with devastating effect.

But the response of Labour’s leadership candidates is instead to ditch some of its most popular policies. The only rational explanation is that they’re responding not to the electorate but the corporate-owned press and the City, who would have had to stump up a bit more if Labour had won and conducted a ferocious campaign against Miliband to prevent any such outcome.

Having secured a Conservative government, the media and business elite now want to ensure an acceptable Labour opposition as well. To that end, the trade unions have become the target for a new onslaught, as the only significant force standing out against a retreat to Blairism.

“Red Len” McCluskey has now replaced “Red Ed” as the main target of tabloid rage. The general secretary of Labour’s biggest union affiliate, Unite, is accused of trying to “hijack” the leadership election after he warned that if the wrong candidate was chosen, pressure would grow in the union to “rethink” its relationship with the party.

That was taken to mean that Unite would withdraw funding or even disaffiliate unless the more centrist Burnham was elected. In reality, there is little enthusiasm for any of the candidates in the main unions, and McCluskey was simply reflecting the fact that it wouldn’t take much for union disillusionment with Labour to tip over.

Until now, Labour’s leadership campaign has been led entirely by an agenda that doesn’t reflect public, let alone Labour, opinion. Last week, 10 newly elected MPs demanded an “alternative to austerity” instead of a return to “the New Labour creed of the past”. But without a candidate prepared to challenge the lurch to the right, the terms of Labour’s debate will be set by the media and Blair revivalists, and the pressure on the frontrunners will be one-way traffic.

The 35-MP nomination hurdle was set to prevent such unwelcome interventions, and one possible candidate, the former miners’ leader Ian Lavery, has ruled himself out because of the threat of media harassment of his family. But Diane Abbott, who stood five years ago, and the shadow cabinet member John Trickett, among others, are ready to stand – and shift the focus of the debate.

One way or another, the wider Labour party needs to take back control of its own contest. If the politics currently paraded by the main candidates wins out, Labour’s prospects in a country where hostility to the Westminster elite has already redrawn the electoral map look bleak. Union disaffiliation could then become a reality and eventually trigger a party split. Where Labour goes now will affect us all.