Tory lead remains at just four points

Latest YouGov poll suggests Labour would remain the single largest party.

The renewed controversy over Lord Ashcroft's tax status and the Conservatives' attack on Labour's relationship with the the trade union Unite have had no effect on either party's popularity, according to a new opinion poll.

The latest daily YouGov survey for the Sun showed no change in any of the three main party's ratings. The Conservatives remain on 36 per cent, with Labour unchanged on 32 per cent and the Liberal Democrats on 20 per cent. If repeated at a general election on a uniform swing, the latest figures would leave Labour 33 seats short of a majority in a hung parliament.

The YouGov figures contrast with those from other polling companies suggesting that the Tories have recovered a comfortable lead over Labour. The New Statesman poll of polls currently suggests that David Cameron would be 35 seats short of a majority in a hung parliament.