John Rentoul: Cameron, the Houdini of Westminster

Shackled by a falling poll lead, policy muddles and photoshopped posters, the Tory leader will be free in an instant

The walls are closing in on David Cameron. The opinion polls are like steel spikes moving ominously closer. The policy furniture that he jammed against the skirting boards is breaking like matchwood. The Tory team that is supposed to be coming to his aid has been taken over by the Tea Party tendency, and is demanding tax cuts as the price of organising a rescue. Our hero – or villain, to taste – seems to be in trouble.

Except that I do not believe that he is. I think he is well placed for the campaign ahead, and that the chances of Labour denying him a workable majority at the election are small. But it is funny how the dominant media narrative can change so quickly.

The story started to change with a trivial error Cameron made on 4 January, the day he launched the Conservatives' new year campaign with a frankly unimpressive poster. The poster itself backfired, becoming notable for its huge picture of him, which looked photoshopped, and a slogan, "We can't go on like this", which spawned a thousand internet mash-ups, which are still going strong a month later. That was also the day he fumbled a BBC interview, when he said a Tory government might not be able to afford a tax subsidy for marriage after all. Three days later, he admitted that he had "messed up" because "I give dozens of interviews every week" – a gambit now known as the Fern Britton Defence, after Tony Blair told the Iraq inquiry that he still had "something to learn" about interviews.

Now the narrowing of the opinion polls over the past eight days has given the story a new twist. The average Conservative lead has fallen from 12 percentage points to nine. Cameron's people point out that this is within the margin of error, but I would not be surprised if there were a bit of controlled panic going on behind the closed doors of the leader's office. Never underestimate the importance of opinion polls in driving political reporting and in determining morale in party headquarters. The timing could not have been worse, then, for the three things that happened last week. First, there was confusion over the Tory message on public spending cuts. It looked as if Cameron had softened the party's stance in the light of Britain's worse than expected growth figure of 0.1 per cent announced the week before. Then a series of right-wing commentators – the Tea Party tendency – called on Cameron to show a bit of true-blue Thatcherite ankle. And finally, Chris Grayling, the Shadow Home Secretary, was told off by the guardian of the sacred impartiality of official statistics for misusing the data on violent crime.

That is how matters are seen in the closed world of the media-political nexus. Out in the wider world, I doubt if much of this registers in the public consciousness. If it does, the information is processed to fit with what people already know. People know two things: that the Tories in government are more likely to keep public spending and taxes lower than Labour; and that crime is a serious problem about which Labour has done too little.

Most voters have more or less made up their minds how they are going to vote. They think Labour has had its chance; they think Gordon Brown has ruined the public finances; they are a bit worried that the Conservatives don't care about unemployment; but on the whole they have decided for change. If there is a real narrowing in the opinion polls it may well be what one wise observer called a case of the "wedding jitters" before the voters commit to Cameron on 6 May.

Yet it is not even clear that the poll gap is closing. The last five polls have given the Tories leads of between seven and nine points, but an accident of timing means that there has not been a poll from ICM, Populus or Angus Reid in the batch, and they tend to put the Tories farther ahead.

And there are still reasons for thinking that the Tories will do better than the polls suggest. Gordon Brown may be preparing for a hung parliament, offering the Liberal Democrats a minimal kind of electoral reform and letting it be known that he won't necessarily stand down as leader if he loses his majority, but that is premature. One reason is that Labour will be fighting an "anti-incumbency effect", as sitting MPs try to defend their expenses claims. Another is that the Tory machine seems to be making real progress in targeting marginal seats. A huge Ipsos-MORI dataset, aggregating all its polls over last year, suggests that the swing from Labour to Conservative is greater in marginals than in safe seats. No wonder Cameron still won't answer questions about Michael Ashcroft's tax status, as the Tory peer is paying for the targeting operation.

Such matters are of great interest, rightly, to journalists. Other journalists are greatly exercised by the contradictions and sheer made-up-on-the-hoofness of the Cameron-Osborne policy machinery. Still other journalists are upset by Cameron's ideological surrender to New Labour. Trevor Kavanagh in The Sun and Fraser Nelson in The Spectator last week demanded massive spending cuts. If they had any power, they would be about as helpful to Cameron as Sarah Palin was to John McCain, but I think Cameron will hold to his strategic course, such as it is.

Of course, all these things will matter when Cameron becomes prime minister. The tax status of his backers, the confusion of his policy and the demented Thatcherism of what Tim Bale, the historian of the rise of Cameron, calls "the party in the media" will be important in government. Because the Tea Party tendency extends from the offices of The Sun and The Spectator deep into the Tory benches in the House of Commons.

But before the election, it seems unlikely that any of these will prove obstacles to Cameron's gentle glide to election victory. Last week, it looked as if the walls were closing in on him. Next week, I suspect, he will, with one bound, be free.

John Rentoul blogs at www.independent.co.uk/eagleeye