The Tories are on course for a crushing defeat at the forthcoming Wakefield by-election, according to a new poll.
In a development that will pile fresh pressure on Boris Johnson, the JL Partners survey gives Labour a 20-point lead over the Conservatives in the key seat.
Voters in the Red Wall constituency - which the Tories gained from Labour at the 2019 election - will go to the polls on June 23.
The vote is taking place after the sitting Conservative MP, Imran Ahmad Khan, quit after being convicted of sexually assaulting a teenage boy.
At the last election, he received the support of 47 per cent of voters, with Labour trailing on 40 per cent.
According to the new poll, which was published in the Sunday Times, Labour are now on 48 per cent, with the Tories on 28 per cent.
The findings are particularly significant because the prime minister is already under huge pressure from his own MPs, with speculation that he could have a vote of no confidence as early as this week.
The House of Commons returns from recess tomorrow, when many expect Sir Graham Brady, chair of the 1922 committee of backbench Tory MPs, to announce that he has received the 54 letters needed to force a vote.
Anger at the PM over the partygate scandal has increased following publication last month of Sue Gray’s report into the affair, which blamed “senior leadership” at the top of government for allowing lockdown-busting parties to take place in Number 10.
One senior Conservative told HuffPost UK: “I know lots of MPs have had really bad feedback from constituents on the PM over partygate at events over the Jubilee weekend.”
According to the poll, swing voters in Wakefield have switched to Labour as a result of their anger over partygate as well as their belief that Johnson has lost touch with working class voters.
James Johnson, the co-founder of JL Partners, said: “All the signs are that partygate has crystallised historic concerns about the Tories and turned the people of Wakefield decidedly against them.”
The PM is also under pressure over the Tiverton and Honiton by-election, which is also taking place on June 23 after the sitting Tory MP, Neil Parish, quit after being caught watching porn in the Commons.
The Tories are defending a 24,239 majority, but the Lib Dems are hopeful of pulling off a major upset.