The Labour leader, Sir Keir Starmer, has urged supporters not to be complacent in advance of the Wakefield byelection, adding that a victory “could be the birthplace of the next Labour government”.

With Labour now odds-on favourites to win back the seat, Starmer shared a message of hope and optimism with supporters at a city centre rally on Saturday, as his party seeks to reverse the Tories’ “red wall” takeover of formerly Labour majority constituencies across the north of England.

Standing on the steps of the Labour party’s regional offices, Sir Keir address a large crowd of supporters alongside Labour’s byelection candidate, Simon Lightwood, and shadow cabinet members Louise Haigh and Jonathan Ashworth. “It feels like we can reach out and touch this. It feels positive. If we get it right, this Wakefield byelection could be the birthplace of the next Labour government,” he told the crowd.

However, he warned supporters to remember to “earn every vote”, adding: “We’ve just got to make sure we don’t take our foot off the pedal now, there’s no complacency. We know how hard this is. We lost in 2019.”

Wakefield was a Labour stronghold since the 1930s, but turned to the Tories in 2019. Labour now has the chance to win back the seat in what Sir Keir referred to as an opportunity to “make history”.

After the resignation of Conservative MP Imran Ahmad Khan, who was convicted for sexually assaulting a boy, the byelection was called with the Tories selecting Wakefield councillor Nadeem Ahmed to defend the seat they won with a 3,358 majority in 2019. Speaking earlier this week, Ahmed compared voter trust in the Tories to faith in GPs despite the crimes of mass murderer Harold Shipman.

The poll is being held on the same day as a byelection in Tiverton and Honiton, which was called after the resignation of Tory MP Neil Parish in April 2022 after he was caught watching pornography in the House of Commons.

The prime minister, Boris Johnson, was expected to visit the constituency on Friday to support the Tory campaign, as well as speak at the Conservatives’ Northern Research Group conference in Doncaster. However, he cancelled to make his surprise trip to Kyiv.