Do not count on the Tories winning just yet

Gordon Brown's government seems to be suffering its death throes. The biggest recession in postwar history. Criminal investigations of MPs who fiddled their expenses. Fewer votes than the UK Independence party in the European elections. Mass resignations of ministers. But even if Mr Brown were to resign tomorrow, the earliest a general election can happen is October; the latest is May next year. This government will be a long time a-dying.

Most commentators assume that whenever the election happens it will be won by the Conservatives. The Labour party had its worst performance in the recent elections since 1910. As in the 1990s, the electorate is sick of the incumbent party. Just as the Labour party had young, telegenic Tony Blair in 1997, so the Tories today have young, telegenic David Cameron.

Yet this is to overstate the strength of the Conservative position. In the European elections, the Tories' total vote rose a meagre 1 per cent. In the local elections, its vote was actually down. If the local results had been replicated at a general election Mr Cameron would have been four seats short of a majority.

The reality is that the electoral position of the Tories is significantly weaker than that of Labour 12 years ago. Opinion polls have the Tory vote hovering between 36 and 40 per cent. This is nowhere near Labour's poll position in early 1995, close to 60 per cent. The polls then probably overstated Labour support but the fact remains that the Conservatives have yet to win over the majority of voters.

Why is this? For one thing, smaller parties have been siphoning off votes. It was not only Ukip and the xenophobic British National party that fared well in the European elections; the Green party won 8.7 per cent and various "others" took 8.4 per cent.

Another reason is Scottish, Welsh and Northern Irish devolution. In the Celtic periphery, the Tories are still perceived as the "English" party.

There are other more deep-seated problems for the Conservatives. Britain has become more socially liberal over the past 12 years. The Labour government is unpopular for many reasons but not for increasing spending on the welfare state. Even as the government's projections show public spending falling from 48.1 to 43.4 per cent of gross domestic product between 2010 and 2013, Mr Brown evidently intends to campaign on the old slogan that the Tories would cut public services, while he would not.

These obstacles to a Tory victory are especially important because changes in demographics and population density have skewed the electoral system against the Conservatives. They need 8 or 9 percentage points more of the popular vote than Labour just to gain an overall majority.

What should Mr Cameron do if he wants to win a decent majority in parliament? He will certainly not succeed by being lured into an argument over public spending. To win some voters he needs to emphasise libertarian themes such as the abolition of identity cards. To win others, he needs to burnish his green credentials by talking about environmentally friendly public transport. A third set come with decentralisation and promises to free local councils from the endless stream of central edicts. Mr Cameron's "Progressive Conservatism" needs to differentiate itself from Thatcherism, which was authoritarian on civil liberties, indifferent to public transport and suspicious of local government. He needs, in short, to lay claim to the political centre.

Yet, at the same time, Mr Cameron can scarcely ignore the strength of sentiment on the political right - not only because of the electoral success of Ukip and the BNP but also because important elements within his own party share their anti-European (if not anti-immigrant) instincts. Indeed, Mr Cameron himself is already committed to a Eurosceptic, right-of-centre European policy. The danger is that Progressive Conservatism ends up being Push-me-pull-you Conservatism, facing both ways.

We are not saying that the Tories cannot win the general election. But it is by no means as certain as many assume. Even now, with the prime minister on his knees, our prediction would be for the Conservatives to be the largest party in a hung parliament or to have only a small majority. It is a long, hard slog that lies ahead.

Niall Ferguson is Laurence A. Tisch Professor of History at Harvard. Glen O'Hara is Senior Lecturer in History at Oxford Brookes University