The Conservatives are struggling to win this election because they failed to win the last one. Most governments endure by managing decline, rather than gaining support. Both John Major and Barack Obama, two leaders whose electoral success Tory strategists study obsessively, retained power with reduced majorities. Because of David Cameron’s failure to win outright in 2010, he will almost certainly fail to do so on 7 May. Indeed, the Tories face a fight to remain the single largest party: Labour needs to make net gains of just 24 seats to supplant them. There is increasing confidence among Ed Miliband’s inner circle that it will.

To win again, the Tories must understand why they fell short in 2010. Their problem is that many still do not. It was a dearth, not a surfeit, of modernisation that denied them outright victory. This is not an ideological assertion but a matter of empirical record. The Conservative pollster Lord Ashcroft’s audit of that election, Minority Verdict, found that too few voters trusted them to manage public services and to govern in the interests of all. In the months that followed, the myth developed that the Tories’ failure derived from the insufficient toughness of their policies on immigration, welfare and Europe. It was one that the party’s becalmed modernisers struggled to contest. After this, the Tories’ rightwards trajectory became inevitable. The “backfire effect”, the term coined by the US political scientist Brendan Nyhan to describe how individuals’ convictions grow stronger in the face of contradictory evidence, took hold.

After failing to decontaminate their brand in opposition, the Tories poisoned it in office. The abolition of the 50p tax rate, the reorganisation of the NHS and the bedroom tax were self-inflicted wounds that have yet to heal. More recent missteps have displayed a remarkable lack of self-awareness for a party that has had 18 years to reflect on its inability to win a majority. For example, this month’s announcement of further welfare cuts was masochistically scheduled to follow an opulent black-and-white ball, a sequence of events more suited to an Evelyn Waugh satire than the campaign of a modern political party.

It is in this context that Tim Montgom­erie, the founder of ConservativeHome, and Stephan Shakespeare, the chief executive of YouGov, have launched “the Good Right”, a new project to regenerate conservatism. They prescribe 12 initial policies for a “One-Nation Conservative Party”, including higher taxes on expensive properties and luxury goods, increased housebuilding, above-inflation rises in the minimum wage, greater infrastructure investment and limits on political donations. It is a programme of precisely the kind that the Tories need to embrace if they are to attract new supporters, most notably the blue-collar voters who have gravitated towards Ukip and who enabled their past majorities. Through a combination of ignorance and arrogance, too many Conservatives have convinced themselves that the economically insecure, interventionist-minded groups attracted to the “people’s army” will be appeased by the promise of an EU referendum, restrictions on migrant benefits and a relentless focus on austerity.

The Good Right has emerged too late in the political cycle to have much influence on the Conservative manifesto currently being assembled by Jo Johnson, Boris’s younger brother and the head of the No 10 policy unit. If its vision is ever adopted, it will more likely follow defeat than victory for the Tories. Referring to Labour’s poll deficit on leadership and economic management, George Osborne has declared that “water would have to start flowing uphill” for the opposition to win. Should the supposedly “unelectable” Miliband nevertheless enter Downing Street, the Conservatives may finally be forced to confront the question of why they are so disliked.

Alternatively, should they scrape over the line, many Tories will greet their victory as a vindication of their ideological prejudices. They will draw comfort from the rejection of Labour’s “socialist” programme, disregarding the individual popularity of many of Miliband’s policies. By again making too little effort to dispel their reputation as the party of the privileged, they will expose themselves to attack from a revived opposition and an economically populist Ukip.

The Conservatives’ historic strength has been their willingness to change according to circumstance. After their landslide defeat to Labour in 1945, they embraced the NHS, the mixed economy and the welfare state and were rewarded with 13 years in office from 1951. Confronted by the exhaustion of the postwar consensus at the end of the 1970s, they produced the transformative philosophy of Thatcherism.

It was in the 1990s that their beliefs ossified into dogma. The doctrine of free-market economics, one not inevitably tied to conservatism, was elevated to the status of a secular religion. Intelligent and practical policies of the kind advocated by the Good Right are now rejected as ideologically impure. A more politically adroit Conservative Party would harness the public discontent against the corporate sector, championing the “little man” in the manner of the trust-busting Republican president Theodore Roosevelt. The current one has rejected a “mansion tax” on the grounds that: “Our donors will never put up with it.”

Should they lose in May, the Tories may yet again draw the wrong conclusions, marching even further into the wilderness of Europhobia. But the party’s economic modernisers would at least have a window of opportunity to shape its future. Defeat to Miliband, a man they will remorselessly ridicule between now and polling day, could be the jolt the Tories need to awake from their dogmatic slumber.