Conservative supporters in areas where the party cannot win should vote for the UK Independent Party on Thursday, according to a Tory think tank.
The Bow Group, which claims to be the oldest conservative think tank, said people should vote Ukip in south Thanet - were Ukip leader Nigel Farage is trying to win - as well as Clacton and Rochester and Strood, which are being fought by former Tory MPs Douglas Carswell and Mark Reckless, as well as in other seats "across the north of England".
The Bow Group has a number of senior Tories on its board and was founded in 1951 by a group of Conservative graduatres. Both Margaret Thatcher, at the time the new party leader, and Edward Heath, the former Prime Minister, spoke its 25th anniversary dinner in 1976.