The Conservatives have appeared to play down their chances of winning the North Shropshire by-election on Sunday after a Cabinet minister said the electorate could use the poll as a “protest vote”.

The by-election, due to be held on Thursday, was prompted by the resignation of MP Owen Paterson, and is for a seat that has been safe for the Conservatives for the vast majority of the last 200 years.

Education Secretary Nadhim Zahawi said by-elections are sometimes used to “send a message”, in what will be read as a hint that the Tories think they could lose the contest, despite enjoying a comfortable majority of almost 23,000 at the last election two years ago.

On top of the sleaze row following the saga involving Mr Paterson, the Prime Minister has been dogged by claims that No 10 broke Covid rules last year by holding a Christmas bash and a festive quiz – a “virtual” event which Downing Street confirmed Boris Johnson took part in “briefly” – in December 2020.

Speaking to Times Radio about the Tory prospects in North Shropshire, Mr Zahawi said: “By-elections have historically been used as a protest vote because people know it’s not going to change the outcome of which party governs the country but actually they want to send a message for whatever reason.

“I think the people of North Shropshire would be really well-served by Neil Shastri-Hurst – I’m certainly backing him and I hope he wins on Thursday night.”

The odds have been slashed on the Liberal Democrats causing a by-election upset, with party leader Sir Ed Davey visiting Wem on Saturday.

Speaking on Sunday, the former Cabinet minister said: “The momentum is now with the Liberal Democrats as we enter the final week of this campaign.

“Every day we are hearing from lifelong Conservative voters who are furious with the Prime Minister for lying, breaking the rules and trying to cover it up.

“They now have an opportunity to tell Boris Johnson that the party is over.”

Labour and the Reform Party – formerly the Brexit Party – are also contesting the seat, along with a slew of smaller parties.

A Conservative councillor in North Shropshire announced last week that he had defected to Reform.

The by-election comes as recent national polls suggest Labour has strengthened its lead over the Tories.

An Opinium survey published on Sunday put Labour nine points ahead of Mr Johnson’s party – the biggest Labour lead in seven years, according to the polling firm.