Boris Johnson has been warned he faces a wipeout in a critical Red Wall by-election this month as he battles to save his premiership.
A new poll gave Labour a 20-point lead over the Conservatives in Wakefield, where voters will elect a replacement for ex-Tory MP Imran Ahmad Khan after he was convicted of sexually assaulting a teenage boy.
The West Yorkshire seat was won by the Tories in 2019 for the first time in decades as Labour's so-called Red Wall fell to Mr Johnson's party.
But constituency polling by JL Partners for The Sunday Times put Labour on 48 points compared with 28 points for the Tories - a 19 point drop from their 2019 performance.
James Johnson, co-founder of JL Partners and a former No10 pollster during Theresa May's tenure, said Partygate appeared to have damaged the Tory reputation among Red Wall voters.
The polling expert said the top reason swing voters in the West Yorkshire seat gave for preferring Labour was because "Boris Johnson tried to cover up Partygate, and lied to the public".
Voters also felt he was not in touch with work class people's concerns.
According to the company, 60% of those interviewed for the survey taken online between May 13-22 had a negative opinion of the Prime Minister.
Pollster Mr Johnson tweeted: "The main hesitations about voting Conservative: trust, Boris, and a sense the Tories are out of touch and only care about the rich.
"All signs are that Partygate has crystallised historic concerns about the Tories and turned the people of Wakefield decidedly against them."
There's also work to do for Labour leader Keir Starmer, who had a rating of -28 (21% positive, 49% negative).
The fieldwork for the survey was done between May 13 and 22, before Sue Gray had published her bombshell report.
Voters will go to the polls in Wakefield and the Devon seat of Tiverton and Honiton on June 23, in a pair of must-win by-elections.
The Liberal Democrats are hoping to inflict a blow on the Tories in Tiverton after being emboldened by local election gains in the south.
Transport Secretary Grant Shapps said it was better to "allow the process to play out" than worrying about polls.
He told BBC Sunday Morning: "I think actually the best thing to do with all elections is to allow the people to speak and do so at the ballot box.
"You often get polls which show a variety of different situations."
Mr Shapps added: "I think it's best just to allow the process to play out. I think we've only got about three weeks, people won't have long to wait and see what does happen."
The PM's leadership is on a knife-edge after Sue Gray's damning Partygate report and mutinous Tories are threatening to trigger a no confidence vote as soon as this week.
Mr Johnson was granted a Jubilee reprieve from Tory plotters but his attempts to enjoy the festivities were marred by booing from the public at a church service and the party at Buckingham Palace.
Officers on the Tory 1922 Committee have reportedly pencilled in Wednesday as the day for a no confidence vote in Mr Johnson's leadership.
Only 1922 chief Sir Graham Brady knows whether enough Conservatives have written letters of no confidence in Mr Johnson to trigger a vote.
54 MPs - or 15% of the parliamentary party - must write to Sir Graham to trigger a vote.
