Bookmakers have made the Liberal Democrats the favourites to win this week’s North Shropshire byelection, odds that if reflected in Thursday’s vote would deliver a significant fresh blow to Boris Johnson’s authority. Lib Dem campaigners stress that the result is hard to predict, given variables such as turnout and the number of Labour and Green supporters who decide to vote tactically. But the party says it is “neck and neck” in the usually ultra-safe Conservative seat, which was held by Owen Paterson in the 2019 election with a near-23,000 majority and has been Tory for all but two of the last 190 years. The byelection was called when Paterson resigned after Johnson abandoned efforts to change the disciplinary system for MPs to save the former environment secretary from being punished for breaking rules on paid lobbying. Although the Lib Dems finished third to Paterson and Labour in 2019, with 10% of the vote, they have successfully positioned themselves as the most likely opposition party to cause an upset, and have been consistently second favourites in voting odds. But following Johnson’s tumultuous week facing claims over lockdown-busting Christmas parties in Downing Street and questions over the financing of renovations to his official flat, bookmakers have the Lib Dem candidate, Helen Morgan, as favourite, at about 1/2. In contrast, the odds for the Conservatives’ choice to replace Paterson, Neil Shastri-Hurst, a Birmingham-based barrister, have lengthened to about 6/4. While the Labour candidate, Ben Wood, has been fighting an energetic campaign and says he is the main challenger, party officials have devoted few resources to North Shropshire. Speaking on Sunday, the Labour MP Yasmin Qureshi effectively acknowledged the party had deliberately left the field clear for the Lib Dems. “Well, it’s realistic,” the shadow Foreign Office minister told Times Radio. “I mean, let’s face it, Labour are never going to win North Shropshire. The Lib Dems do have an opportunity to do so. “It’s not just soft-pedalling, I do think that in constituencies like these ones, where Labour don’t have a huge amount of resources … we know, realistically, we have no chance of winning.” Another imponderable is the strength of support for the Greens’ candidate, Duncan Kerr, given strong local election results for the party last May, giving it 12 of 18 council seats in Oswestry, the constituency’s biggest town. Overall, the result remains very difficult to call, with other complications including a notably short campaign, in which some locals received postal votes before the parties had a chance to contact them. A key factor could be how many traditional Conservative voters who are now dissatisfied with the party and with Johnson decide to stay at home on Thursday, or even to vote Lib Dem. Daisy Cooper, the Lib Dems’ deputy leader, who spent the weekend campaigning in North Shropshire, said support for the Conservatives there “has collapsed”. She said: “We are now neck and neck with the Conservatives and our campaigners are flooding into the constituency from across the country. “As we enter the final few days of the campaign, the crucial question is: will enough Labour and Green voters vote tactically for the Lib Dems? If they do, this could help deliver a knockout blow to Boris Johnson.”