The Conservative Party has “failed to see the threat from the Liberal Democrats” while focusing too much on Reform, Theresa May has warned.

Writing in The Times ahead of the party’s annual conference in Birmingham, Baroness May said the remaining candidates for the Tory leadership could “play into Reform’s hands” by failing to understand why they lost the general election.

The former prime minister said the Conservatives lost power in July not due to policy, but because the party had “trashed our brand”, losing its reputation for “integrity and competence”.

Blaming the Partygate scandal and Liz Truss’s mini-budget, Lady May added the Tories had spent “too long tacking to the right in order to appease potential Reform voters” and “forgot that we are not a right-wing party but a centre-right party”.

Tory leadership frontrunner Robert Jenrick in front of a sign spelling out his surname
Tory leadership frontrunner Robert Jenrick has focused his campaign on immigration (PA)

Lady May compared the Conservatives’ strategy to last month’s 1,500m Olympic final in Paris, in which Norway’s Jakob Ingebrigtsen was too focused on defeating Britain’s Josh Kerr that he allowed American Cole Hocker to come through on the inside and 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.”

Her intervention comes ahead of a Conservative conference that will see former ministers Robert Jenrick, Kemi Badenoch, James Cleverly and Tom Tugendhat continue their battle for the party leadership.

The four candidates will each have an opportunity to address the conference, and their campaigns will be lobbying MPs before parliamentarians pick the final two on October 10. Members will choose between those two, with the result declared on November 2.

Kemi Badenoch delivers a speech during her Conservative leadership bid
Kemi Badenoch accused her rival Robert Jenrick of engaging in ‘dirty tricks’. (James Manning/PA)

Even before they had arrived in Birmingham on Saturday, most of the leadership contenders began setting out their pitch for the coming days in interviews and op-eds for national newspapers.

Immigration has so far featured heavily in the leadership campaign, with frontrunner Mr Jenrick making it a centrepiece of his campaign and arguing the party’s defeat was 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 said: “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.”

James Cleverly delivers a speech from behind a lectern with the slogan 'Cleverly for leader'
James Cleverly focused on tax rather than immigration in his editorial for The Daily Telegraph. (James Manning/PA)

Meanwhile, Ms Badenoch used a Times interview to accuse Mr Jenrick’s campaign of engaging in “dirty tricks” by lending votes to Mr 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.”

Mr Jenrick’s campaign has denied Ms Badenoch’s allegations.

Mr 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 “have work to do”.