After more than a month of campaigning, postal ballots are expected to be issued soon to the around 160,000 Conservative party members as Rishi Sunak and Liz Truss are set to take part in a live leadership programme hosted by Sky News.
Some in the audience remain undecided about who they will vote for, meaning this debate could be crucial in helping them make up their minds.
One audience member is Sue Lumby, a councillor from North Yorkshire.
The 71-year-old says she is going to the debate with an open mind and says there is a chance she could change her mind at the last minute.
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“I think both Rishi Sunak and Liz Truss are good candidates in that they are very different. We have a very clear view on what they both believe. So I think that’s good. I think they’re both honourable people.”
“I like Liz Truss because she’s quite direct. She’s not polished on camera and I like that. I think she’s been a very good foreign secretary. International Relations is very important when it comes to how we conduct ourselves with other countries and our neighbours. That’s very, very important and she has certainly got that in her pocket.”
I think Rishi Sunak handled the COVID crisis as chancellor really rather well.”
Sue says the debate could prove pivotal.
“It all depends on how they perform. It may reinforce my views, it might change my views. Who knows.”
The winner will be decided once all the votes have been counted and Britain will have a new prime minister on 5 September.
Claire Greenfield lives in Solihull in the West Midlands and she is a loyal Conservative.
But the leadership hopefuls still have some persuading to do if they are going to get her vote when she takes her seat in the audience on Thursday.
“So at the moment, I’m undecided between Rishi and Liz. I am leaning towards Liz Truss more. And so this debate will hopefully make up my mind as a member of the Conservative Party and I can cast my vote with confidence,” she said.
“I’d like them to give us a manifesto and then actually stick to it. That would be the main thing. Obviously, the economy is a terrible worry at the moment with inflation and costs. The defence of the country is also very important to me also.
Claire says she has doubts about Mr Sunak’s motivations to become PM, and Ms Truss’s recent climb down over her policy to determine the salaries of public sector workers based on where they live has also made her decision a difficult one.
“Rishi Sunak seems a decent chap. I think he supported the country very well with COVID. However, the thing I don’t like about him is the I do feel he stabbed Boris in the back.
“I like the fact that Liz Truss has been strong on the international stage, especially against Putin, and she’s been in the room with everything that’s been going on.
“However, I was disappointed yesterday with this U-turn and I wondered whether this something that’s going to be a carry on the previous Boris government carried out a lot of U-turns.
“I’ve never been to a televised debate and I’m very much looking forward to it. I want to take in the atmosphere and get the chance to see these two politicians face to face and get a real sense of what they believe in. And then that will help me make up my own mind.”
Taking place on Thursday 4 August at 8pm at Sky Studios in west London, The Battle for Number 10 will see the candidates take part in back-to-back questioning from the live studio audience made up of Conservative Party members who remain largely undecided on who to vote for.
This will then be followed by an in-depth interview with Kay Burley.
The programme will be broadcast live for 90 minutes and for free on Sky News channel 501, on Freeview 233, on Sky Showcase channel 106, and across Sky News’ digital channels.