John Rentoul: Cameron – evasive but unstoppable

The Leader of the Opposition can afford to take more risks, because he is going to win the election anyway

A Cabinet minister once described David Cameron to me as "like one of those grabber machines in a Blackpool arcade. It looks as if you should be able to pick up the soft toy, but you cannot."

It does look as if Cameron should be picked up easily – and taken apart. Last week, for example, he gave an interesting and important speech on taxes and public spending. The most pressing issue facing an incoming Conservative government, he said, would be the debt accumulated by Labour, with outgoings continuing to exceed income by a large margin. What to do? "The richest in our society must bear a fair share of the burden," he said. "We will reduce this deficit together. The poorest in our society should not pay an unfair price for mistakes made by some of the richest."

Instead of saying directly that taxes will have to go up, especially for the rich, however, it was left to spin-doctors to explain what he meant afterwards. A typical New Labour device for handling a tricky policy shift. Conservative sources said that his words meant that, in government, he would go ahead with the new 45p rate of tax on incomes over £150,000 a year, which Alistair Darling announced in November, to start from April 2011.

By such evasiveness, the internal Tory reaction was delayed. It was a day later that Tim Montgomerie, webmaster of the party's internet grassroots, and Boris Johnson, who still wants to be prime minister, attacked the policy.

At the same time, though, the Conservatives remain committed to a tax cut for the rich – raising the threshold for inheritance tax to £1m. You will be ditching that, then, I suggested to a well-placed Tory. "It is a commitment we have made and we're not going back on it," I was told. I understand that the policy goes down very well with the focus groups. They do not see it as being about "the rich", but about aspiration.

Really, Cameron should be taken apart on this hypocrisy. I am told that the Tory leader does not think it worth taking on his party over this as well as the 45p rate. But two and a half years ago, Cameron put a statement of aims and values to the vote of his party that included this: "The right test for our policies is how they help the most disadvantaged in society, not the rich." It was approved by 93 per cent. There are senior Labour people who are terrified that Cameron might force his party to mean what it said. But he does not need to, because he is going to win anyway.

And why should Cameron go farther than Labour in announcing tax rises, when Darling is going to have to announce more new taxes – to take effect under a probable Conservative government – in next month's Budget, because the public finances have deteriorated so badly since November? Let Labour take the hit and then quietly accept it afterwards.

His speech also talked of tough choices without actually making them when it came to public spending. Public spending would have to be "controlled" under a Conservative government, he said. Except on the NHS – and on international development, which is a tiny part of the total budget. But on the rest, he half-implied, huge savings could be made. Except that the only examples were high pay for quangocrats, the national children's database and identity cards.

Well, attacking the "quango state" is what oppositions do (Labour certainly did); governments replace old quangos with new, even higher-paid ones and then decide to keep half the old ones anyway. The children's database is a terrible idea, but much of the money will have been spent by this time next year. And as for identity cards, the expensive bit is the register, which you have to have if you want to count everyone in and out of the country, as the Conservatives do.

If Labour had confidence in what it was doing, it would take all this apart. But it has lost the plot, distracted by the machinery of governing. There is still a core that will put up a fight, notably Brown himself. Alastair Campbell, with no formal position of greater standing than guest editor for one week only of the New Statesman, is a one-man masterclass in political campaigning. I am reminded of the slightly too colourful words of Richard Wilson, Tony Blair's Cabinet Secretary, as he tried to explain why Campbell was paid by the taxpayer to attack the Tories. As long as he doesn't "go over the top ... with bricks and bottles", Wilson soothed. Well, it is bricks and bottles now.

Campbell had sport with Daniel Finkelstein on the radio yesterday, as Finkelstein, who once worked for John Major, tried to say that Cameron had transformed the "tone" of the Conservative party, rather than its policies. Campbell mocked him, justifiably. With the possible exception of schools policy, Conservative preparations for government seem to lack seriousness.

Yet it hardly matters. Most of the Labour Party has given up. Not because of the lack of a desire to win, but because of the lack of leadership. Brown does relentless and he does strategy, but he does not do explanation or inspiration. Not on television anyway, which is what counts. His address to the joint session of the US Congress was a fine speech, but it was an assemblage of soundbites, not an argument.

One of Blair's greatest failings was that he did not bring on a generation of leaders to take over after he went. So, while Cameron makes big, persuasive speeches that do at least point him in the right direction, the Labour Party allows itself to be distracted by the smallness of the contest for the succession to Brown after what it regards as certain defeat.

Cameron resists definition. He talks about tough choices without ever really making any. He will, therefore, easily defeat Gordon Brown, a known quantity. The grabber in the Blackpool arcade cannot get a grip on him. His core beliefs are ungraspable. In other words, as an electoral force he is unstoppable.