The Conservative Party is heading for a heavy defeat in the Corby by-election in November, according to one of the party's biggest donors.
Lord Ashcroft said a poll carried out in the Corby constituency vacated by Louise Mensch would "almost certainly" become a Labour seat.
According to a poll carried out in the constituency by the Tory peer, Labour currently has a 15-point lead: 52% to the Conservatives’ 37%, with the Liberal Democrats on 7%.
Writing on the Conservative Home website on Thursday, Lord Ashcroft said if the swing to Labour was repeated at a general election, Ed Miliband would easily be able to form a majority government.
"Voters are pessimistic about the economy, and are more likely to say the government is doing badly than that it is doing well; few think the Conservatives share their values, will do what they say, or are on the side of ordinary people," he said.
However the peer did find one crumb of comfort in the numbers, as he said it was "perhaps surprising" that the Labour lead was not even bigger in Corby.
Corby had been a Labour seat from 1997 until 2010, when it was captured by Mensch. However after serving just two years as an MP the author-turned-politician announced she was struggling to juggle her personal and professional life.
Mensch intends to move to New York with her three children to be with her husband.