The Greens are locked in an internal debate about how hard to challenge Andy Burnham in the Makerfield byelection, with some members worried about allowing Reform UK to win and others wanting their party to go all-out.

While characterised by insiders as “very civilised”, the discussion has highlighted existing differences between Greens who believe concessions can be won from Labour through informal cooperation and others – including some newer leftwing activists – who argue it achieves little.

While it is ultimately up to the local party whether to field someone in the byelection, which is expected to take place next month, a candidate appears set to be announced on Wednesday.

Zack Polanski, the leader of the Greens in England and Wales, and those around him, will need to decide the amount of resources to devote to the campaign.

In February’s Gorton and Denton byelection, the Greens overcame a 13,000-plus Labour majority to defeat Reform UK and push Labour into third place, mobilising thousands of activists to flood the constituency with canvassers, posters and leaflets.

One senior Green said: “The debate is what the campaign would look like. There is a world of difference between turning up to the hustings with a bit of leafleting and what we saw in Gorton and Denton. Throwing everything at it would be up to the national party.”

Makerfield is also in Greater Manchester, but very different to Gorton and Denton, and seemingly much less favourable to the Greens, who finished fifth in the constituency in the 2024 general election.

Caroline Lucas, the former Green MP who was the party’s first MP, has led calls for the party not to overly impede a return to Westminster for Burnham.

Lucas said on social media: “There are times when it’s more important to put country before party. This is one of them.

“Burnham’s longstanding commitment to a fairer voting system could transform our democracy and counter the dire threat of a Reform UK government.”

Others in the party disagree vehemently, saying Burnham cannot be trusted and that it is not the Greens’ job to help Labour.

Not all of them are newer members. Jenny Jones, a veteran Green activist who is one of the party’s two members of the Lords, has argued that the party is “not a pressure group” to be stood down when needed.

She said: “We are a political party that owes it to voters to give them the chance to vote Green. Plus, this is a mess of Labour’s own making. They are playing games. We are looking to replace them.”

Others in the party, however, argue that it is in the Greens’ best interests to extract commitments from Burnham, notably on proportional representation, which he supports, while not scuppering Labour’s chances in a byelection seen as central to efforts to push back against Reform UK.

Another senior Green said: “There are some people who see the big threat to the country being a Reform government, and the idea that there is little sense winning lots of Green seats if Nigel Farage is then in charge.”

The decision on allocating resources would ultimately be up to the party’s executive committee. While Polanski is just one of about two dozen members, his view is likely to be crucial.

One Green source said that, so far, Burnham did not seem to be offering a programme that aligned with the party’s priorities, and that he had played a role in a “pretty awful” anti-Green campaign in Gorton and Denton.

“We don’t know which Andy Burnham version will turn up,” they said.