The Conservatives are braced for a hattrick of by-election losses that would make Rishi Sunak the first prime minister since Harold Wilson to suffer three defeats in a single day.
In a result one senior Tory said would be “disastrous”, voters could eject the party from every constituency up for grabs.
There were, however, signs of growing optimism within the party on Thursday that they could hold one of the three formerly safe seats.
The votes were called after Boris Johnson and his close ally Nigel Adams dramatically quit parliament, prompting accusations of “mutiny” from a fellow Tory MP.
Mr Sunak has warned his MPs they face a "tough battle", cautioning that governing parties rarely win by-elections.
One former minister predicted the results would be “disastrous”.
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A Tory peer said: “I don’t know anyone who thinks it will be anything except three losses”.
A former cabinet minister also described two of the three seats as “well away” but said he thought the party could potentially save one.
As the parties’ expectation management got underway on Thursday, Labour sources emphasised it would require a big swing towards them – and not just disillusioned Tory voters sitting at home – to take Mr Adam’s Selby seat.
Mr Johnson sensationally stood down as an MP last month, accusing a parliamentary committee of a witch hunt designed to force him out over the Partygate scandal.
Former prime minister Boris Johnson— (PA Wire)
Within days his close ally Mr Adams had also resigned. The third contest was called after Tory MP David Warburton quit after admitting cocaine use amid allegations of sexual harassment.
Labour hopes to take both Mr Johnson’s former seat of Uxbridge and South Ruislip and Selby and Ainsty, previously held by Mr Adams. The Liberal Democrats, meanwhile, are confident of victory in Somerton and Frome, Mr Warburton’s old seat.
Earlier this week Mr Sunak refused to comment on speculation he could perform a reshuffle of his cabinet on Friday, after the results are declared. But his official spokesman said on Thursday there were “no plans” for Mr Sunak to change his top team.
— (EPA)
Senior Tories have sought to write off the results by blaming the former prime minister and what they called the “long Boris” effect. But Tory MPs will be nervously scanning the results for signs of whether or not their woes can be blamed on the previous administration.
At the last election, Mr Johnson took Uxbridge in outer London with a majority of 7,000 majority.
The other two seats have much larger majorities - Mr Adams took Selby and Ainsty in North Yorkshire with a 20,000 majority, a similar margin to Mr Warburton's victory in his Somerset seat.
Lib Dem leader Sir Ed Davey has said voters can use the by-elections to send a message to Mr Sunak on the NHS, the cost-of-living crisis and protecting rural communities.
Sir Keir's spokesman downplayed Labour's chances, saying the party had not won Uxbridge even during its landslide victory in 1997 and that taking Selby would require the party's best by-election result since the Second World War.
