At the start of this month, endur­ing the worst period of his leadership, Ed Miliband faced a defining choice. He could seek to appease his critics, those who denounce him as “anti-business” and charge him with pursuing an unambitious “35 per cent strategy”, or he could stand his ground. He chose the latter path.

“It was as if a jolt of energy surged through him,” says one adviser, of the moment Miliband reaffirmed his faith in his political project. Since his “fightback” speech on 13 November, the Labour leader has been engaged in a permanent offensive: assailing Sports Direct for its endemic use of zero-hours contracts, rebuking opponents of a mansion tax, targeting “cowboy employment agencies” and opening a new front against private schools. His strategy has been that of Ferdinand Foch, the French First World War general: “My centre is giving way, my right is retreating, situation excellent, I am attacking.”

Miliband’s confidence is partly attributable to the recent promotion of two long-standing allies: Jon Trickett, a senior adviser and shadow minister without portfolio, and Lucy Powell, the shadow Cabinet Office minister and his former chief of staff. Trickett, a radical socialist, has encouraged him to “pick fights” with predatory companies, while Powell, now vice-chair of the election campaign, is regarded as having brought greater decisiveness to his operation.

At moments of weakness, opposition leaders have frequently abandoned their original course. William Hague, Iain Duncan Smith and Michael Howard all set out to “modernise” the Conservatives but soon retreated under pressure to the right. Rather than performing an equivalent volte-face, Miliband has doubled down on his strategy of siding with “the many” against “the few”. In so doing, he has returned to the territory of his greatest political victories: his deft response to the phone-hacking scandal, his energy price freeze coup and his counter­attack on the Daily Mail for its misrepresentation of his father, Ralph Miliband.

Miliband’s allies acknowledge that as a PPE graduate and former special adviser he will never be seen as an outsider, making it even more imperative to embrace bold and distinctive stances on the economy. The aim is to deny Ukip the chance to bracket Miliband with David Cameron and Nick Clegg as part of the “LibLabCon” hydra.

It is a mistake to interpret the recent fall in Labour’s support as evidence that the party has strayed too far from Blairism or the assumed “centre ground”. Were this the case, one would have expected voters to gravitate towards the Conservatives and the Liberal Democrats. In practice, it is Ukip, the SNP and the Greens who have benefited as the public punishes a Labour Party regarded as having changed too little, not too much.

Margaret Thatcher, Tony Blair and, to a lesser extent, David Cameron all won by defining themselves against both the government of the day and their parties’ former incarnations. Cameron’s failure to achieve a majority reflected the incompleteness of his modernising project. Miliband is conscious of the need to avoid a similar fate.

But if there are potential rewards from his strategy there are also risks. Some in Labour fear that their leader’s rhetoric of struggle is insufficiently optimistic to rouse a nation all too aware that it is enduring a “cost-of-living crisis”. One MP argues that “people don’t want to be reminded how bad their lives are”. There is a tension between Miliband the radical, who talks of sweeping away three decades of neoliberalism, and Miliband the incrementalist, who talks gently of building a “fairer capitalism” and reveres consensual “one-nation politics”. A Labour source laments that his recent “pro-business” speech to the CBI was followed three days later by an “anti-business” address.

But the party believes it can marry the two approaches. One strategist speaks of how Labour will be both “fighters” and “builders”. By confronting vested interests, the party will create the conditions for a better capitalism to emerge. The recent assault on exploitative employment agencies, for instance, was coupled with a commitment to create an extra 400,000 engineers by 2020. Ed Balls, who is well regarded in the City of London, has warned business that the only way to maintain public support for an “open-market economy” is to reform dysfunctional sectors such as energy and banking. Miliband’s recent invitation to the CBI to forge a “partnership” for change, combined with avoidance of an EU referendum, will be a recurring theme.

The hope is that if Labour can achieve a sustained period of competency, free from self-inflicted wounds, the glare of scrutiny will return to the Tories, where Theresa May shamelessly flaunts her leadership ambitions and Owen Paterson, recently evicted from the cabinet, is making an early bid to head the EU “out” campaign. In a reversal of historic form, it is the right, not the left, that engages in weekly faction fights.

Among the opposition, MPs ponder the implications of Miliband’s defiant stand. The most hostile are relieved that any defeat will now be on his terms, denying supporters the chance to pin the blame on the Labour right. Others are troubled by what one calls “the Hollande problem”: the difficulty of meeting expectations of a transformed economy and of enacting austerity far greater than any mainstream politician dare say. Confronted by the surging anti-establishment tide and fraying party loyalties, some in Labour fear 2015 could be a narrow victory from which they never recover.

The Tories’ hope remains that voters’ longing for security and stability will dissuade them from gambling on Miliband. By remaining true to his original vision, the Labour leader has guaranteed one thing: whatever the outcome of this most unpredictable election, he will own it.