Andy Burnham has proposed reviewing the increase in employers’ national insurance contributions and cutting business rates for independent firms in his first significant policy move during the Makerfield by-election campaign.

The Greater Manchester mayor said Labour had “got it wrong on small businesses”, in a notable public criticism of Keir Starmer’s policies. Under his plan, pubs, clubs and music venues would receive a 20% business rates cut next year, while smaller independent hospitality, leisure and retail firms would benefit from a raised threshold for paying the tax, the first such change since 2017.

The cuts would be funded by higher levies on large warehouses run by online retailers such as Amazon, and charges targeting owners of empty high street properties.

On national insurance, Burnham said: “I have said that I thought the weight of the burden on employers’ national insurance wasn’t the right decision. However, it was the decision. There is more that needs to be done to listen to the voice of small business, and as I’ve gone around this constituency, I’m hearing it a lot. People just feel they are at the kind of limits of what they can do.

“I am willing to be honest about where we have fallen short and say that my party has got this wrong in government. Our high streets matter to me because they matter to the people who live here. I want to make sure that these family-owned businesses, as the heart and soul of this country, are protected and given the chance to thrive.”

Burnham is standing in the by-election on 18 June, a contest triggered after sitting MP Josh Simons stepped aside to make way for him. He has confirmed his intention to challenge Starmer for the Labour leadership if elected.