Brown bounce or Cameron crumble?

It should not have been a particularly good week for Gordon Brown. The apparently doomed Prime Minister trudged into the final month of the year with little credible hope of salvation in 2010.

The economy remained stubbornly in recession. Separate studies suggested poverty under Labour was enduring and manufacturing withering. And, yet again, Mr Brown was embroiled in a row over letters of condolence to the families of Britain's war dead.

On top of these blows to his capability on domestic affairs, he faced trouble on the overseas front: public disagreements with the French and Pakistani leaders, and the cloying discomfort of the ongoing Iraq inquiry.

So, why is it David Cameron who as he heads for the Christmas break is the more anxious of the two over the shifting sands of his standing in the polls? A couple of political embarrassments for the Tory leader and an unusually vibrant Brown performance at PMQs have suddenly switched the focus of the political game: the election result is no longer as predictable as it seemed two months ago.

Then, after Labour had sunk to 26 per cent in the polls despite a decent Brown performance at the annual conference, the veteran pollster Sir Bob Worcester characterised the party's plight as "dismal". Nevertheless, he warned that with an increase of just 3 per cent in the Labour vote, on a turnout at the 2005 level of 61 per cent, "even a Tory lead of 10 points could result in a hung parliament".

It is the Tories' worst electoral nightmare: a remarkable political resurrection, a huge lead in the polls, but still not enough to win a general election on their own. And, as the events of the past few weeks have suggested, it just may be coming to pass.

Since October, Labour has been plodding back in the polls. Two weeks ago, an Ipsos Mori poll suggested the gap had closed from 17 points to six points in just a month. "If Labour could get [its own] voters to go to the polls," Sir Bob pointed out, "the party would be in with a chance."

It is a requirement recognised by those attempting to hatch a rescue plan for the Government. The strategy they have alighted upon to enliven these dormant supporters is old-fashioned class war. More than a year after the "Tory toffs" strategy failed at the Crewe and Nantwich by-election, Mr Brown announced its return at PMQs this week. Mr Cameron, the "modern public relations man", was offering "tax cuts for millionaires", and an inheritance tax policy "dreamed up on the playing fields of Eton".

The assault on Mr Cameron's background, his old school, and how his adviser and Tory candidate Zac Goldsmith had enjoyed favourable "non-domiciled" tax status, was not simply a joyous response to a one-off political opportunity. Downing Street aides confirm that this line of attack will be repeated "on a daily basis" in the run-up to the election.

"This isn't just about envy," an aide said last night. "Drawing attention to Cameron's background is a legitimate way of exposing the weaknesses in his economic policies as a whole."

The Labour hierarchy have gambled the house on their electoral fortunes improving as the UK recovers. The irony is that a "class war" strategy is designed to capitalise on the mistrust and division engendered by continuing recession. Labour can track an improvement in their standing after the shadow Chancellor, George Osborne, began to flesh out his own austerity measures during his speech to the Tory conference in October.

The message has been received by the Opposition, and senior figures in Mr Cameron's team have urged against being seen as the party willing to do "the dirty business" over taxation and, in particular, cutting public spending. The Tory leader has become increasingly agitated by the Labour attacks – indeed today he tells the BBC that the class-war strategy is "petty, spiteful and a stupid thing to do. But if that's what they want to do, then go ahead."

The criticism will encourage Labour strategists, who this month head to Washington for a summit on advanced internet campaign techniques with Barack Obama's winning team.

"You write this guy off at your peril, mate," a senior Brown aide said, after the performance on Wednesday. Yet he could have said the same last year, when a 15-point Tory lead in September had dwindled to just four points by December. By the new year, the gap was back into double figures again.

Mr Brown's "recovery" this time needs to be sustained, rather than a blip, as a winter revival next year will be at least six months too late.