The Conservatives are badly trailing Labour in two of their key Labour-held target seats, and are effectively neck and neck with the UK Independence party there, according to polling conducted by Survation and commissioned by a Ukip donor.
The polls show Labour with an 18-point lead over Ukip in second place in Great Grimsby and with a 20-point lead over the Conservatives in Dudley North. Great Grimsby is the Tories' 10th target seat and Dudley North their ninth.
The polling suggests that 70% of the Ukip vote is not coming from Conservative voters in the 2010 election.
In Great Grimsby the poll shows Labour on 40% (33% in the 2010 election), Conservatives 20% (31%), Liberal Democrats 13% (22%), and Ukip 22% (6%). In Dudley North there is also a Tory collapse with Labour on 45% (39% in the 2010 election), Conservatives 25% (37%), Liberal Democrats 2% (11%) and Ukip 23% (9%). These figures exclude those who say they are unlikely to vote, or those undecided.