Rishi Sunak's Tories risk losing more than 1,000 council seats at the local elections in May, according to a new analysis.
Elections experts Colin Rallings and Michael Thrasher said Keir Starmer's Labour Party could scoop 700 seats if there is a swing of 6% from the Conservatives.
The result would be dire for Mr Sunak and could potentially reignite the civil war within the Tory Party - just a year out from a general election.
In the analysis published for the Local Government Chronicle on Monday the two experts said the Tories are defending around four in 10 of all vacancies.
They said: "A 6% swing from the Conservatives to Labour since 2019 could see Conservative seat losses breaching 1,000 with Labour registering 700 or so gains.
"Such a swing is rather less than current polling suggests, but even in the Blair era, Labour struggled to match its poll rating with local votes.
"Anything far outside those parameters will provide succour or pain accordingly.”
Speaking on Monday the Tory peer and elections expert Lord Robert Hayward also stressed the Conservatives have the most to lose when voters head to the polls.
The party is defending 3,290 council seats across the country on May 4 - compared with 2,062 for Mr Starmer's Labour Party and 1,205 for the Liberal Democrats.
In total, 8,141 council seats are up for grabs in 230 councils across England.
The peer said the Conservative brand had been "seriously damaged" by Mr Johnson and Liz Truss's 49-day Government that spooked the financial markets.
He added there was "no question" that mass strikes across the public sector, including the NHS, had had a "deterrent effect" on the Tories.
But he also claimed the impact of Mr Johnson on the Tories' poll rating appeared to be "diminishing".
While he said he still expected the Conservatives would lose seats in May, he would not expect the losses to be as great as if the elections had been held a few weeks ago.
"He (Mr Sunak) may be pulling the Tory party up. What seems to be happening is, the longer he is in as Prime Minister the less of an impact Boris/Partygate is having," he said.
"The population have not parked Partygate. They still view it as a Tory party matter but they are viewing it as a Boris matter," Lord Hayward added.
