The media column - Peter Wilby savours the columnist's discomfort

The Tory leader writers sounded as if they had discovered mouse droppings in a relative's kitchen, b

As Bruce Anderson wrote in the Sunday Times, "there are moments when the commentators need to sack all their concepts and assumptions".

Indeed yes. David Cameron's rebranding of the Tories presents challenges for all commentators. For years, the left-wing columnists have demanded that Tony Blair commit to closing the gap between rich and poor, call big business to order, and get serious on the environment. Meanwhile, right-wing columnists have dismissed global warming stories as left-wing propaganda, berated politicians who wish to confiscate the hard-won gains of the rich, and insisted that health and education should be largely privatised.

On the right, Anderson, a ubiquitous commentator and a former political editor of the Spectator, passed his test with flying colours. He is a party man who once wanted to write for the NS but, he told me, could not possibly criticise the then Tory leader, Iain Duncan Smith. If the leader says white is black, Anderson's previous assumption that white is white will be duly sacked. In a spirited defence, he argued that Cameron had to "accommodate himself to public opinion".

Simon Heffer, by contrast, is not a party man, but a Thatcherite. Cameron claims to deplore all isms, including capitalism, and Heffer is a walking ism. Like the classy ideologist he thinks he is, Heffer, formerly of the Mail, now a Daily Telegraph columnist, dismissed Cameron's approach as "not really of an intellectual standard worthy of my wanting to engage in debate with it".

The Tory papers' leader writers sounded as if they had discovered mouse droppings in a relative's kitchen, but didn't want to mention it. Cameron's full-page New Year advertisement in the Sunday Telegraph (presumably his advisers thought the deep-blue background, which made much of the text almost unreadable, would soften the shock of what he was saying) was "trenchant", said the Daily Telegraph the next day. But it would "raise the odd eyebrow" among Conservatives.

Three days later - after Cameron had dropped Tory commitments to subsidise private health patients and after Heffer's eyebrows had disappeared in the direction of the Andromeda galaxy - the Telegraph took the tone of an irritated schoolmaster. It had supported the boy's application for a scholarship ("Well, sort of," the parents might interject) and remained "well disposed" towards him. But it was "disappointed". It concluded: "In time, Mr Cameron may well settle down to his schoolwork" - sorry, "may well produce clear policies for reforming the NHS".

The boy failed to learn his lesson. A few days later he withdrew the Tory pledge to bring back grammar schools. He was now guilty of "strategic myopia". A sentence further on, as if hearing a small voice ask "Is that Latin, sir?", the master's patience finally snapped. Cameron was "plain wrong", thundered the Telegraph.

What of the left-wing commentators, who found Cameron moving Aneurin Bevan-side of Blair and suddenly espousing all the things they hold dear? Most were having none of it. Yasmin Alibhai-Brown in the Independent didn't believe a word Cameron said, reminding us "he wrote, yes wrote, the Tory manifesto in the last election". In the same paper, Johann Hari demolished the record of Zac Goldsmith, Cameron's new green guru. New Labour's faithful foot soldiers were as equal to their test as Anderson was to his. In the Guardian, Polly Toynbee saw it all as confirmation that Blair had shifted the landscape: to be outflanked on the left was his "glory moment".

But there were wobblers. In the Evening Standard, Jeanette Winterson confessed she might vote for Cameron because "I am desperate about the environment". In the Observer, Henry Porter, with the air of a monk hovering outside a brothel, admitted that "well, yes, I could". Most dramatically, the Observer editor, Roger Alton, in an interview in the trade magazine Press Gazette, described Cameron as "a bright, engaging bloke". He "wouldn't have thought it was inconceivable" that his paper could support Cameron at the next election - which is brave of Alton, given the abuse he got for backing the Iraq war, not least from within the Guardian Media Group.

As for the floating voters, there's only one the Tory leader will care about: Rupert Murdoch. His intellectual hit man, Irwin Stelzer, hinted in these pages last year that News Corp's support for new Labour wouldn't necessarily transfer from Blair to Gordon Brown, because of the latter's liking for "high-tax, high-regulation, state-expanding policies". Now, in the Sun and the Guardian, Stelzer detected in Cameron the same horrors of income redistribution, with the added outrages of windmills and organic food.

"Given a choice between the real thing - Gordon Brown - and a pale copy, it would be unwise to expect voters to choose the latter," warned Stelzer. Since, in Stelzerese, "voters" means Murdoch, it sounds bad for Cameron. By 2009, I fear, Bruce Anderson will be issuing a P45 to another set of concepts and assumptions.