The four Conservative leadership candidates are preparing for their final chance to address the party’s conference in their race to be Rishi Sunak’s successor.

Optimism, the party’s future and the economy will be among the topics touched on when Robert Jenrick, Kemi Badenoch, Tom Tugendhat and James Cleverly address delegates in Birmingham on Wednesday.

Their contest has been the focus of the four-day gathering as the party looks to rebuild after the general election loss in July.

The final session comes the day after Mr Jenrick suffered a backlash from his rivals for claiming that UK special forces were “killing rather than capturing” terrorists.

The Newark MP is the frontrunner in the contest, and is expected to use his speech to call for a “new Conservative Party” if it wants to “tackle the immense challenges” it faces.

“If I become our leader, this is what – together – we will build,” he will say.

He will also set out the changes the party will have to make, including a rejection of mass migration and a focus on building.

Mr Tugendhat will set out his plans for a “new Conservative revolution” in areas such as the economy and housing.

“I will build an economy that works for you,” he is expected to say.

Ms Badenoch is also expected to focus on economic policy and pitch that the Conservatives “have to be the party of wealth creation”, while Mr Cleverly will tell members to be “enthusiastic” and “optimistic”, and that they will win back the electorate by being “professional”.

The Tuesday conference headlines were dominated by Mr Jenick’s comments from a campaign video released earlier this week in which he suggested the British military is taking lethal action because of fears that European human rights laws would free any detained assailants.

Mr Tugendhat called the claims an “extremely serious allegation” and suggested people should not “comment on military matters you know nothing about”.

Former security minister Mr Tugendhat told a conference fringe event: “It is an extremely serious allegation and without very specific examples it would be… irresponsible to do that.”

He added: “If you present a legitimate military threat to the United Kingdom, then we have under the laws of armed conflict today a legal ability and in fact a military capability to conduct operations to keep the British people safe.

“I am afraid that is simply a fact, and if you don’t know it please don’t comment on military matters you know nothing about.”

Mr Cleverly suggested during a main stage Q&A that Mr Jenrick must “justify” his claims.

Elsewhere, Ms Badenoch claimed that as many as a tenth of civil servants are “very bad” at their jobs.

She joked that some were “‘should be in prison’ bad”, drawing laughter from the audience at a Spectator magazine event.

Ms Badenoch said: “I think that civil servants are like everybody else. They come in to do a job and I would say about 10% of them are absolutely magnificent.

“The trick to being a good minister is to find the good ones quickly, bring them close and try and get the bad ones out of your department as quickly as possible.”

“There is about 5% to 10% of them who are very, very bad. You know, ‘should be in prison’ bad,” she added.

After days of trying to persuade members and colleagues in Birmingham, the leadership candidates will be whittled down from four to two next week by the parliamentary party before the membership gets the final say.

The winner of the contest is due to be announced on November 2.