The Conservatives' lead over Labour has risen to four points in the first opinion poll to be conducted since the Budget.
The latest daily YouGov survey for the Sun put the Tories up one point to 37 per cent, with Labour down one to 33 per cent and the Liberal Democrats up one to 18 per cent. The previous day's poll showed the Tories' just two points ahead of Labour, the party's lowest lead since December 2008.
But the survey still suggests that Labour could survive as the largest single party in a hung parliament. If repeated at a general election, the latest figures would leave Gordon Brown 25 seats short of an overall majority.