Reform UK has overtaken the Tories in a series of opinion polls in recent weeks, and is within touching distance of Labour’s lead with the public.
Kemi Badenoch has rejected a suggestion the Tories could merge with Reform UK to beat Labour in the next election.
The Conservative leader also criticised the actions of Tory-led governments she served in, including leaving the EU without a “proper” plan, as she made her first major speech of 2025.
Nigel Farage’s Reform UK has overtaken the Tories in the opinion polls in recent days, and is within touching distance of Labour’s lead with the public.
Asked about a possible merger with Mr Farage’s party in order to beat Labour, Mrs Badenoch replied: “Nigel Farage says he wants to destroy the Conservative Party. Why on earth would we merge with that?”
She added: “Nigel Farage has been knocking around for 20-plus years. He’s been leading all sorts of different parties, so he has had a head start.
“I’ve been leading the Conservative Party for 10 weeks. Let’s see where we are in a few months and years.”
The Tory leader acknowledged her party had made mistakes over initiating Brexit under the leadership of Boris Johnson and Theresa May, as well as on immigration in recent years.
She told a central London audience of Conservative members and journalists: “We were making announcements without proper plans. We announced that we would leave the European Union before we had a plan for growth outside the EU.”
She added: “We announced year after year that we would lower immigration, but despite our efforts, immigration kept going up.
“Those mistakes were made because we told people what they wanted to hear first and then tried to work it out later. That is going to stop under my leadership.”
Asked about the negative tone of her speech, Mrs Badenoch insisted she was “doing a serious job”.
She added: “I’m speaking based on where the Conservative Party is. We have just suffered our greatest ever defeat.
“I don’t think the public will start trusting us if I turn up looking like I’m having a great time and everything’s fantastic.”
