Bruce Anderson: Cameron is at his best when the threat is greatest

David Cameron is at his best in adversity. August 2005: David Davis seems to be building up a commanding lead in the Tory leadership contest. Some of Mr Cameron's friends are worried; his camp appears to be inactive. David Cameron calms everyone down, insists that the real campaign will not start until September, and has a short break in Italy. August 2007: Gordon Brown seems to have reinvented himself, and won a sizeable poll lead. A lot of Tories are losing sleep, but not David Cameron. "Gordon should enjoy himself," the Tory leader would say. "This is as good as it gets."

Over the past couple of weeks, it has looked as if that assessment was over-optimistic. The black secrets of the Brown personality, long known to those around Westminster and above all to his ministers, have been exposed to the general public. The Chancellor of the Exchequer refers to "the forces of hell" which Downing Street launched against him. Gordon Brown denies responsibility; yes, and Macbeth was innocent, OK. One might have though that the revelations about the MacBrown regime would have finished off the PM. On the contrary; the poll gap has been narrowing – and Tory nerves have been tensing.

Not Mr Cameron's. What he said yesterday was true; he had expected the poll lead to shrink as the election approached. He never thought that this would be an easy campaign. If Gordon Brown would unleash the forces of hell against Alistair Darling for telling the truth about the economy, what would he not do to the man who was telling the truth about the country and trying to drive him out of No 10? Mr Cameron always assumed that this would be a bare-knuckle fight.

But he did not do enough to convey that message to his colleagues and to ensure that there was more bloodied fist in the Tory strategy. Since Christmas, the Tory message has been too diffuse and too thoughtful. There has been no attempt to simplify the themes and sharpen the language. Although David Cameron has acknowledged the need to do this, he has not done enough to make it happen.

A number of Tories blame this on Steve Hilton, one of Mr Cameron's closest friends and advisers. It is true that Mr Hilton would never be on the anti-intellectual side of a debate. If he were offered the choice between a tried and tested approach and an original one, his instincts would always be on the side of originality. But it would be unfair to hold him solely responsible for a collective failure.

Equally, and although there have been stresses, a bit too much has been made of a supposed crisis session in Notting Hill last week. There was no crisis, merely a meeting of close advisers to review progress, or the lack of it. But this is hardly unprecedented.

The Cameroons have spent many an evening around each others' dining tables. They argue; what else would one expect from a group of highly intelligent and opinionated characters who all have strong views on complex subjects? Sometimes they have the sort of heated discussions which would make for a terrific dinner-party, with everyone texting the next day to say what fun that was and let's do it again soon. All this has nothing in common with the incessant, black-bile rages which have rendered this government dysfunctional. For a start, the Cameron team like and respect each other.

Even so, there will be a switch of emphasis. Between now and polling day, the streetfighters will be in charge. Their gang of three might seem oddly assorted. As one would expect, it includes Andy Coulson, who used to edit the News of the World. But unlike, say, Rebekah Wade or Kelvin MacKenzie, Mr Coulson is a mild-mannered fellow. His confreres are George Osborne and George Bridges.

Mr Osborne may be the heir to a baronetcy, but he does not look like the sort of pugilistic Regency baronet who would have consorted with the fancy. Mr Bridges is a grandson of Lord Bridges, sometime head of the Civil Service and one of the most formidable Whitehall chiefs of the 20th century. Young George Bridge's bloodline is high administration, not low politics.

In the other corner – not that they would go anywhere near a boxing ring – are Steve Hilton, the son of a Hungarian refugee, and Oliver Letwin, a former Cambridge don who is the offspring of American academics. Each team has one old Etonian, but background, class and education are irrelevant. These are able men who have formed their own political views. They all know that at the end of the dinner party, David Cameron will take the decisions.

Early on, Mr Cameron decided that yesterday's speech would be another high-wire act. With neither notes nor a lectern for protection, it was trapeze artistry without a safety net. In previous noteless forays, Mr Cameron had memorised chunks of the text. This time, he merely worked out a structure and then improvised. The final product lacked the molto vivace of his finest party conference performances – 2005, 2007 – but there was plenty of excitement. Moreover, this will not be a stand-alone speech. It was his opening salvo in the intensified phase of the election campaign.

Assuming that there are 10 weeks to go, we can only make one confident prediction. This will be one of the most important election campaigns of all time. Over the past 30 years, the majority of election campaigns had little effect on the outcome, which would have been roughly the same if the poll had been held before the electioneering started. This time, there is a lot of volatility out there. The debates could have a dramatic impact. So could general perceptions of the party leaders. There is also a lot of disillusion. A large number of voters are more in a mood to call down plagues on all the parties than to feel enthusiasm for any of them. That could change, or it could intensify, especially in a long campaign.

That said, enough voters may have come to one settled judgement which could be decisive. In the polls, Gordon Brown trails his party; David Cameron does better than his one. Yesterday, viewers could see why. Even when he is not at the top of his game, Mr Cameron has an electricity which his rivals cannot match. He must now use that voltage to generate trust.

In part, he can do this by talking about hope and change, themes which come naturally to him. He should also use the vocabulary of aspiration, which has not been prominent enough in Tory rhetoric. Although that is partly because of the economic crisis, wise Tories never lose contact with the language of opportunity. Under him, Mr Cameron promised, "Britain will be open for business". There needs to be more of that.

Yet the Tories have another problem, which might seem to need a different solution. They have to appeal to the angry classes; the people who think that the country has gone to the dogs and who feel more punitive than hopeful. Some of yesterday's proposals on immigration and welfare will help, but they will need to be repeated. For the next few weeks, there needs to be a bit less tree-hugging and a bit more bunny-boiling. Not to mention Brown-bashing, though a large number of Tories are still hoping, despite the recent polls, that he will manage to bash himself.