England’s newest metro mayor has said she would “move heaven and earth” to ensure her party holds on to her former constituency as it was revealed Labour members would choose their pick to replace Tracy Brabin on Sunday.

Applications are open for the candidacy for the Batley and Spen by-election, with the party’s National Executive Committee (NEC) to draw up a shortlist on Saturday and members choosing the final pick on Sunday, sources confirmed to the PA news agency.

And while it has not yet been announced when the by-election triggered by former MP Ms Brabin’s election as West Yorkshire mayor will be, speculation is that late July is being considered.

Speaking during a visit to a bus factory in North Yorkshire with London mayor Sadiq Khan, Ms Brabin said she would “move heaven and earth” to make sure Labour won the race.

Kim Leadbeater, sister of murdered former Batley and Spen MP Jo Cox, has announced she will be putting her name forward.

Ms Brabin said: “I’m from Batley and Spen so working with Jo Cox and then, after her murder, becoming the MP for my region was a huge privilege. I’m determined that we’re going to keep Batley and Spen Labour.”

Jo Cox commemorative events
Kim Leadbeater, the sister of Jo Cox (Jane Barlow/PA)

“Kim is an exceptional woman but there’s other candidates, as my understanding, so it will be down to the constituency Labour party to make that choice.

“But, to be honest, whoever is the candidate, I’ll move heaven and earth to make sure we keep Batley and Spen Labour and I think we’ll do it.”

Ms Leadbeater, who established the Jo Cox Foundation in honour of her sister, said she would take her “more in common” message into her campaign if selected by Labour.

After a visit to the People’s History Museum in Manchester, where an exhibition dedicated to Mrs Cox’s work opened on Wednesday, Ms Leadbeater said: “The exhibition is called More In Common and that is one of the messages I intend to bring to the forthcoming by-election if Labour Party members choose me as their candidate.”

She told the Spenborough Guardian: “Anyone who knows me or has met me knows that I’m very much my own person. I’m not Jo. I couldn’t be Jo if I wanted to, and our parents always taught us to be true to ourselves, so that’s my promise to myself and everybody.

“I’m Kim. And what you see is what you get.

“I’ve got my own views, my own priorities, my own ideas and dreams for the future of this area.

“If Labour members do me the honour of supporting me, I’ll repay that trust by working my socks off for them and for the whole of Batley and Spen. We have a great future ahead of us as a community and nothing would make me prouder than to work with local people and to champion Batley and Spen at Westminster.”

Mr Khan said Labour needed policies and a vision to persuade people to vote for the party after losing the Hartlepool by-election to the Tories.

He said: “Batley and Spen have had two brilliant Labour MPs recently, both friends of mine, Tracy and Jo. I’m hoping we select a candidate equally as good as Tracy and Jo.

“I understand the challenges with the bounce the Government has with the vaccine rollout and we’ve got to make sure we work incredibly hard, going door to door, street to street, community to community, to listen to and persuade people why they should lend us their vote in the by-election.”

Others rumoured to be interested in standing include Paula Sherriff, the former Labour MP for Dewsbury.

Lisa Johnson, external relations director for GMB union, and Salma Arif, a Leeds council cabinet member, had also been mooted but have both ruled themselves out.

It is understood the selection could have been carried out sooner, however the chaos surrounding the sacking of Angela Rayner as party chairman is thought to have slightly delayed the process

The race is seen as a key test for Labour leader Sir Keir Starmer after the party lost the Hartlepool by-election to the Conservatives earlier this month.

A Conservative Party spokesman said their candidate would be announced “in due course”, however a source said it could be as soon as this week.