General Election 2015: Ashcroft poll puts Ukip 'within striking distance' in marginal seats

Ukip is neck-and-neck with the Tories in three target seats

Ukip are challenging the Conservatives in three marginal seats (Carl Court/Getty Images)

Ukip is within striking distance of winning three of their key target seats from the Conservatives at the general election, an opinion poll suggested this morning.

In the Essex constituency of Castle Point, where Nigel Farage last week held a campaign launch, Ukip is polling just one point behind the Tories.

In the Lincolnshire seat of Boston and Skegness, which has become a Ukip local government stronghold, the party was three points behind, winning 35 per cent support against 38 per cent for the Tories.

There is a six-point gap in another Essex constituency, South Basildon and East Thurrock, with Ukip on 29 per cent and the Conservatives on 35 per cent.

In all three seats a substantial minority of voters opted for Labour, meaning that both the Tories and Ukip will devote huge resources to persuading them to vote tactically on May 7.

There was better news for the Tories in North East Cambridgeshire where they are in a comfortable 21-point lead despite a swing to Ukip.