Boris Johnson arrives for the Platinum Party at the Palace (Picture: REX/Shutterstock)

Boris Johnson could face a crunch vote on his premiership as new polling suggests the Conservatives risk being pummelled in an upcoming by-election.

A survey of voters in Wakefield, who will elect a new MP on June 23, predicts the Tories could lose by as much as 20 points.

It would be a damning indication that revelations about Downing Street lockdown parties have badly damaged the Prime Minister’s popularity.

The PM secured his landslide 2019 majority off the back of scalps in the so-called Red Wall, with traditional Labour-supporting areas in the North of England, the Midlands and Wales switching their support to the Tories.

But the Wakefield polling, reported in The Sunday Times, will make anxious reading for Tory campaigners, with Labour on 48 points to Mr Johnson’s 28 – a 19 point slip on his winning performance two-and-a-half years ago.

The poll findings come amid reports the threshold for a no-confidence vote might have been reached, with suggestions a leadership test could be coming as soon as Wednesday.

Polling expert James Johnson said the so-called partygate saga looked to have damaged the Tory reputation among Red Wall voters.

He said the top reason swing voters in the West Yorkshire seat – who are voting for a candidate to succeed former Tory incumbent Imran Ahmad Khan after he was found guilty of sexually assaulting a boy – gave for preferring Labour was because ‘Boris Johnson tried to cover up partygate, and lied to the public’.

According to the poll, 60% of those interviewed between May 13 to 22 had a negative opinion of the PM.

James 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.’

The PM also faces a second test in the Tiverton and Honiton by-election on the same day as Wakefield.

Last month, an investigation published by senior civil servant Sue Gray laid bare the details of a host of Covid rule-breaching gatherings.

The inquiry found that raucous parties had taken place, with staff throwing up, getting into altercations and being rude to security staff.

The PM was found to have attended a number of leaving dos for aides, giving speeches and joining in the drinking of alcohol, despite him at the same time telling the public not to see sick and dying loved ones in a bid to stop the spread of the virus.

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