On a wall inside Andy Burnham’s buzzy campaign centre, the signatures of hundreds of MPs, peers and councillors show the scale of the operation to return him to parliament. “MPs are like buses round here these days,” says one Labour volunteer. “You don’t see one for ages then hundreds turn up at once.”

The voters of this long-neglected corner of Greater Manchester will on Thursday decide whether Labour’s love-bombing has paid off in the most consequential UK byelection in decades.

Barely 24 hours before voting begins in Makerfield, the polls suggest Burnham will triumph, and Labour figures sound increasingly confident.

“It’s really positive,” beams the Labour MP Rachael Maskell as she climbs into a car piled with Burnham-branded leaflets on Tuesday afternoon. “I’ve had people take down Reform posters and come back to Andy because they can see it’s so divisive. In the last minutes of reaching a decision [voters] are turning to Andy because he’s bringing people together.”

Maskell, who led a rebellion against disability cuts last July, says Labour has “found its values and purpose again” in Makerfield and urged Burnham to launch an immediate leadership challenge if elected.

Asked whether he could be prime minister by the Labour party conference in September, Maskell says: “I’m optimistic that can happen very quickly … This country is crying out for his leadership.”

Constituency polls have given the Greater Manchester mayor between a three- and 12-percentage point lead over Reform. While the “Burnham bounce” is real, the result may be decided by another party entirely: the rightwing Restore Britain.

Rupert Lowe’s hardline party, which calls for the death penalty and mass deportations, is predicted to win about 7% of the vote in what would be an astonishing result for an outfit that launched only four months ago. It would also be enough to stand in the way of Reform.

“If Restore weren’t around Reform would walk it,” says Darren, the Reform-supporting owner of the Triangle snooker club, where Farage hosted a party event last week.

Darren, who declines to give his surname for fear of losing customers, says Labour has “hammered” the ground war but the split among the rightwing vote is likely to prove decisive: “Restore will take those votes that will push it Andy Burnham’s way.”

On the streets and on social media, the energy appears to be going in two directions: to Burnham and Restore. A Guardian analysis shows Restore has bought more Facebook and Instagram advertising on Makerfield than any other party – and more than double the number of Reform.

Outside the Triangle club in Stubshaw Cross, Reform’s open-top battlebus, plastered with posters of its candidate, Rob Kenyon, a plumber, sits empty.

Its driver, Trevor Jones, was elected as the Reform leader of Bolton council in May and takes the bright teal bus across England for party events. He is used to the odd insult but this campaign, he says, has been “more aggressive than I’ve ever seen”.

Restore Britain activists were filmed last week blocking Reform’s bus with a union flag-branded Land Rover and Jones says some had tried to plaster it with Restore posters: “We should be fighting the same cause not one another. I bet Burnham is laughing his head off.”

Voters across this semi-rural stretch of former mining villages south of Wigan, where 95% of the population is white British, said the byelection had become increasingly toxic.

There were reports of Labour placards being torn down, neighbours falling out and divisive rhetoric on local Facebook groups, which a study found this week have been swamped with pro-Reform misinformation.

Speaking beside a Reform placard outside her neat semi in Stubshaw Cross, Pam Flaherty, 70, says people are “turning against each other”. “I had one man spit at my poster,” she says. “He stood there effing and blinding and I’ve known this man for years.”

Flaherty, a retired nursery cook, and her husband, Ian, 69, were lifelong Labour voters but joined Reform over concerns about immigration. Pam is now a member of Restore Britain but will vote for Farage’s party on Thursday.

“People say I’m racist but I’m not. My knee surgeon was Pakistani, he’s a lovely man; my dentist is Egyptian and my doctor is Indian – I love them,” she says, adding that she worries about “letting every Tom, Dick and Harry in on the boats and taking over”.

Burnham may be peeling off a small slice of Reform voters, says Prof Rob Ford, of the University of Manchester, but the swing is “mainly coming from a squeeze on Lib Dem and Green voters” and “substantial numbers of Tories”, according to polling data.

This anti-Farage coalition is based largely in the suburb of Orrell, the most affluent part of the constituency, where Burnham placards are far more numerous than any other.

“This community has been neglected since Thatcher and people are really angry but we’ve got two groups, Reform and Restore, coming in stirring that anger towards the wrong people,” says Mal Jones, 64, normally a Green voter, who will vote Labour on Thursday.

Jones, a former social worker, says he has seen groups of burly Restore activists “abusing people” and that both rightwing parties are “dividing the community”, adding: “It’s like something from 1930s Germany.”

His friend, Peta Prescott, 48, is another Green voter backing Burnham. She worries about whether the area will be able to come back together after such an intense and polarised campaign. “I don’t know if people realise how far right they’ve fallen,” she says. “They’re just swept up in ‘Stop the boats’.”

Four miles away in town of Hindley, Lynne Tindall, 70, and the staff at Izzy’s tea room were in raptures about Restore, whose leader visited them on Saturday. None would say who they will vote for but they were full of praise for Lowe, whom they had not heard of before this byelection.

“We need to send the immigrants back,” says Tindall. “We will be a minority in our own country soon.”

Her friend, Carole Dowd, 64, agrees: “They’re everywhere. It’s like they drop them in the middle of the night. We’ve got no money because we’re giving it to them.”

Helen McDonough, 55, praised Lowe and insisted none of them were racist, pointing to the “lovely lad” who owns the barber shop next door, Hajar Abbasi.

Abbasi, 32, who is Kurdish and arrived in Britain nine years ago, said his neighbours at Izzy’s tea room were “really nice to me” and brought him free cakes.

But the hostility towards immigrants has left him afraid, he says, one of the reasons he will vote for Burnham: “I’m very worried about this. They are thinking that all immigrants or black people do bad, bad things.”