A “protest vote” in North Shropshire could see the Tories lose their safe seat in Thursday’s by-election, a Cabinet minister has said, as Labour plans to bus in hundreds of volunteers for the final days of the campaign.

Nadhim Zahawi said voters in the constituency could “send a message” to the Government by unseating the Conservatives for the first time since its creation.

A source close to the Labour campaign said it plans to have between 200 and 300 Labour volunteers on doorsteps in the constituency this week, up from just 40 at the beginning of the campaign six weeks ago.

Despite bookmakers’ predictions that the seat will fall to the Liberal Democrats, Labour believes it has a better chance of eliminating a majority of 23,000 votes in the area, which was previously held by Owen Paterson.

Labour sources dismissed rumours that the party had struck an unofficial pact with the Liberal Democrats to stand down their campaigners and avoid splitting anti-Tory voters.

Alleged Downing Street party last Christmas

Mr Zahawi, the Education Secretary, on Sunday pointed to angry emails he had received from constituents about an alleged party for Downing Street staff at Christmas last year.

“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,” he told Times Radio.

A Conservative campaign source said Tory bosses “certainly aren’t complacent” about the vote, which they described as a “tough fight”.

“The last few days has seen a lot of Labour literature going out and their vote is well motivated,” the source said.

Leaving no stone unturned

Labour this week also plans to take out a front cover wraparound advertisement in the local newspaper in North Shropshire, send leaflets through the door of “almost every house in the constituency,” and erect billboards urging voters to choose its candidate, Ben Wood.

Party sources said its ability to fight by-election campaigns had been hampered by Labour’s cash crisis, which follows a series of expensive lawsuits against former staff in Jeremy Corbyn’s office.

Many Labour volunteers are said to be taking holiday from work this week to travel to the constituency and campaign.

Sir Ed Davey, the Lib Dem leader, said yesterday: “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.