The Conservatives' lead over Labour has narrowed to eight points in the first opinion poll to be published since Gordon Brown called a general election.
The latest daily YouGov survey for the Sun put the Tories down one point to 40 per cent, with Labour up one to 32 per cent and the Liberal Democrats down one to 17 per cent. If repeated at the election on a uniform swing, the latest figures would leave the Tories 10 seats short of an overall majority in a hung parliament.
But in practice, since the Conservatives are likely to perform disproportionately well in the marginals, an eight point lead should be large enough give David Cameron a small Commons majority.
Fieldwork for the poll started at 5pm on Monday night and finished on Tuesday afternoon, meaning that the majority of responses came in before Gordon Brown announced that the general election will be held on 6 May.