Election '97: If you aren't a switcher, forget it 1/45point

Tony Blair wants to know you, but only if you live in one of 57 key constituencies, writes John Rentoul

If you want Tony Blair to take you seriously, you have to live in one of 57 target constituencies, tell the Labour Party that you voted Conservative last time, and say you haven't yet decided this time.

Then you will feel wanted. You will have received a "personal" letter from the Labour leader as soon as John Major went to the Palace to ask for the dissolution of parliament. You have probably been invited to meet Mr Blair, and the local Labour candidate has been on your doorstep more than once.

Labour's election campaign is based on the concept of targeting. Mr Blair needs to win just 57 seats to have a majority of one in the new House of Commons, and in those seats, taking boundary changes into account, the Tories won by a combined margin of just 146,000 votes in 1992. So, if 73,000 people can be persuaded to switch their allegiance from Tory to Labour, Mr Blair will be sure of becoming prime minister. That is why the key word in the Labour worker's lexicon is "switcher".

This is the small group of voters highlighted on Tuesday by Liberal Democrat leader Paddy Ashdown who said the parties were cynically targeting the marginals at the expense of the electorate at large.

The trick is to work out who the 73,000 people who matter in this election actually are. It is a trick the Labour Party is getting better at, and it remains well ahead of the Tory party in the science of political targeting.

In the 1992 election, Labour achieved a higher-than-average swing in its target seats, worth an extra 1,000 votes in each one and as many as 25 extra seats. This time, they mean to do better than that.

All the party's canvass returns from the last election are on a series of linked computer databases, and these have been maintained and updated so that Labour knows more about the voting history of its target voters than many of them can remember themselves.

All voters are classified into different kinds, including weak Labour, "positive" Labour, squeezable Liberal Democrat, and the all-important Tory "switchers". Not all the effort is put into switchers, because the computer database is also the foundation for Labour's GOTV effort - an acronym imported from the United States, meaning Get Out The Vote.

But the big effort is on those who might vote Labour but are not persuaded yet. If Labour identified you some time ago, you will already be used to receiving regular communications from Mr Blair, his deputy, John Prescott, and the local Labour candidate. But it is not just leaflets. Shadow cabinet members are taking time out from preparing to run the country to talk on the telephone to potential switchers who might be swayed by their soft words.

Now, however, Labour faces the strange possibility that they may be, like generals, fighting the last war. Even if the opinion polls are as wrong as they were last time, the real battleground is not going to be these 57 seats at all, or even the 90 which have been designated "key seats" to give Labour a buffer, to allow for some targets to be missed.

Unless the Tories turn the campaign round quickly, Labour could win in all kinds of unlikely seats where its preparation has been much less intense.