Before Ed Miliband announced his plan to freeze energy prices for 20 months from May 2015, he and his aides knew that it would "be big". They had long been struck by polling showing  that rising gas and electricity bills were voters’ primary concern, ranked above wages, employment and housing. But even they have been surprised by the extent to which the policy has defined political debate since the conference season. Three weeks on from Miliband’s speech, the Labour leader's team believe it has had even more impact than George Osborne’s 2007 pledge to raise the inheritance tax threshold to £1m, with "huge cut through to the public" in the words of one aide. (A poll  published yesterday showed that voters rate it above all the other policies announced by the parties during the conference season.) To their satisfaction, the Tories have struggled to settle on a consistent line of attack, unsure whether to dismiss it as a "gimmick" or as dangerously "left-wing", or to match it in some form.
The policy was devised by Greg Beales (jokingly named "Mr Freeze" by his colleagues), Miliband’s director of strategy and planning, who had long urged the party to shift its focus away from the macroeconomy and towards living standards. It was a reorientation inspired by Barack Obama’s 2012 election campaign. In meetings with the Labour team in London and Washington DC, Obama aides including his pollster Joel Benenson emphasised how important the president’s stance on living standards had been to victory in tough times. A report on the election by the veteran Democrat Stan Greenberg for Miliband pointed to polls showing that while Mitt Romney had led on "handling the economy"(51-44%) and "reducing the federal budget deficit" (51-37%), Obama had led on understanding "the economic problems ordinary people in this country are having" (51-43%) and on "looking out for the middle class" (51-40%).
This left-right split is mirrored in the UK, where a recent ComRes poll  found that voters think the Conservatives (42%) are more likely than Labour (33%) to maintain economic growth and keep public spending under control (47-28%), but also that they believe their own family would be better off under Labour (41-31%).
Labour is confident this trend will favour it in 2015. As the economy enters a post-crisis phase, the party believes voters will become less concerned with macro issues and more concerned with whether their family is sharing in the proceeds of growth.
After missing their original target of eliminating the structural deficit in one parliament, the Tories have sought to turn economic failure into political success by emulating Obama’s 2012 campaign message and urging voters to let them "finish the job". But they have failed to recognise that Obama was referring not to government borrowing but to living standards. As for the warning "not to give the keys to the guys who crashed the car in the first place" – similarly inspired by the US president – a Labour aide pointed out to me that Obama "actually ran on that line in the 2010 midterms and it was a disaster".
The Tories have derided Miliband’s focus on the "cost of living" as a distraction from the primary task of "fixing" the economy, but this message is ill suited to a time when 11 million people have had no increase in their real earnings since 2003. Aware of this, the Tories are preparing a barrage of cost-of-living measures for the Autumn Statement but, more than at any other point since 2010, they will be forced to fight on enemy territory.