The Tories' lead over Labour has continued to narrow despite the government's troubles, according to two new opinion polls.

The latest daily YouGov survey for the Sun put the Tories down two to 36 per cent, with Labour one point down to 32 per cent and the Liberal Democrats up one to 20 per cent. If repeated at a general election on a uniform swing, the latest figures would leave Gordon Brown 31 seats short of a majority in a hung parliament.

With just weeks to go before the expected election date of 6 May, Tory strategists will be troubled by polls suggesting that Labour could emerge as the single largest party after the election.

Meanwhile, a new Opinium survey for the Daily Express showed the Tories' lead falling four points to seven per cent. The poll put the Tories down two to 37 per cent, with Labour up two to 30 per cent and the Lib Dems down one to 15 per cent. Other parties are on an unusually high 18 per cent. If repeated at a general election, the figures would leave David Cameron 23 seats short of a majority in a hung parliament.