The Conservatives “failed to see the threat from the Liberal Democrats” while focusing too much on the rise of Nigel Farage’s Reform UK, Theresa May has said. Writing in the Times on the eve of the party’s annual conference in Birmingham, Lady May said the remaining candidates for the Tory leadership could “play into Reform’s hands” by failing to understand the reasons behind their electoral humiliation. The former prime minister said it was not policy that caused them to lose power, but the party “trashing our brand” and losing its reputation for “integrity and competence”. Blaming the Partygate scandal and Liz Truss’s mini-budget, May said the Tories had spent “too long tacking to the right in order to appease potential Reform voters” and “forgot that we are not a rightwing party but a centre-right party”. She compared the Conservatives’ strategy with last month’s 1,500m Olympic final in Paris, in which Norway’s Jakob Ingebrigtsen was so focused on defeating Britain’s Josh Kerr that he allowed the US’s Cole Hocker to take gold. She said: “Just as Ingebrigtsen was focused on Kerr and failed to see that his action against him would open up other threats, so the Conservative party has been focused on Reform and failed to see the threat from the Liberal Democrats – losing 60 seats to them at the election.” May resigned in 2019 after intense pressure from her party during Brexit negotiations. Her three-year premiership was marked by turbulence as the party entered a prolonged internecine spat over Britain’s departure from the EU. She was replaced by Boris Johnson, her former foreign secretary, who had previously resigned in protest over May’s approach to Brexit, accusing her of leading the UK into a “semi-Brexit” with the “status of a colony”. At the Tory conference, which begins on Sunday, the former ministers Robert Jenrick, Kemi Badenoch, James Cleverly and Tom Tugendhat continue their drawn-out battle for the party leadership. The candidates will each have an opportunity to address the conference before parliamentarians pick the final two on 10 October. Party members will then choose between those two, with the result declared on 2 November. Immigration has so far featured heavily in the leadership campaign, with the frontrunner, Jenrick, making it a centrepiece and arguing the party was defeated because it broke its promises on immigration. In an interview with the Daily Telegraph on Saturday, he said he wanted to “put Nigel Farage out of business”, and described Reform as “a symptom not a cause”. He added: “It exists in its current state because my party failed. We made promises on issues that millions of people … small-c conservatives like me, care passionately about, like controlled and reduced immigration, like securing our borders, and we didn’t deliver on those promises.” Meanwhile, Badenoch used a Times interview to accuse Jenrick’s campaign of engaging in “dirty tricks” by lending votes to Cleverly in an effort to keep her out of the final two. She said: “If the MPs try and stitch it up, I think the members will be very angry.” Jenrick’s campaign has denied Badenoch’s allegations. Cleverly, the former home secretary, focused on tax rather than immigration in an op-ed for the Daily Telegraph, saying Labour’s election attack line that the Conservatives had raised the tax burden to its highest level in decades showed the party had “work to do”.