Labour members and supporters are not optimistic about the party’s chances of winning the Peterborough by-election on Thursday, if the latest LabourList survey is anything to go by. Perhaps that has something to do with events on the weekend before polling day, when it emerged that Lisa Forbes had liked Facebook posts describing Theresa May as a “Zionist slave master” and “enjoyed” a thread that claimed ISIS was created by the CIA and Mossad. Although the Peterborough candidate swiftly apologised, it was also found that she had signed a letter opposing the International Holocaust Remembrance Alliance definition of antisemitism, which was at the centre of party infighting last summer. The Jewish Labour Movement, an affiliated group, has said it will not be campaigning for Forbes this week as a result.

Many Labour activists were not put off from trying to get Forbes elected, however: it is estimated that around 300 canvassed in Peterborough on Saturday morning. Jeremy Corbyn gave a speech to a large crowd. I missed it, unfortunately, arriving instead as volunteers ate their lunch outside the campaign headquarters. Knowing one of the activists taking a break between canvassing sessions, I asked how warm the reception had been so far.

80% of promises were holding up, he said, and data apparently looked good. Although Peterborough voted by 60.9% to Leave in 2016, he had mostly spoken to Remainers on the doorstep that morning. As anti-Brexit campaigners within the party are always keen to point out, Labour’s 2017 voters in Leave seats chiefly opted to Remain. (Of course, the real immediate question is whether Labour as a Remain party would hit a ceiling with only Remainers on board, and the real long-term debate is over whether we are happy with our gradual shift away from Leavers, recognising that 2017 Labour voters are different from 2005-2010 Labour voters.) Some were thinking about switching from Labour to Lib Dem or Green, the activist told me, but it wasn’t overly difficult to win them around.

On the doorstep myself, I had a good response rate with many families resting at home during Ramadan. The key lines given to canvassers at HQ were around issues of policing (88 local police officers have been cut, contributing towards a 48% rise in crime), schools (underperforming due to austerity) and poorly-run local services (the council is under no overall control but run by the Tories). None of these concerns were raised by the voters I spoke to, who either confirmed they were supporting Labour or were uncertain but not keen on a longer conversation. This was to be expected, as the weekend before polling day is pure get-out-the-vote (GOTV) time.

When I was able to draw out voter concerns and start a deeper discussion on the doorstep, we covered the profiles of the candidates – emphasising that Lisa Forbes, a Unite the Union organiser, was a true local having lived here for 30 years – and Brexit. One man, who voted Remain in 2016, thought there should be another referendum. It was a casual belief, not an all-consuming one, simply based on the idea that the first result was a close call. Worried about his financial position (“what will Brexit do to my mortgage?”), he was curious about the parties’ respective positions. I explained Labour’s position of wanting to avoid no deal, which could require a public vote of some kind. He seemed more definite about voting Labour after we talked over the risk of the Brexit Party winning on Thursday.

Matt Turner, former editor of left-wing website Evolve Politics and former Fiona Onasanya staffer, reckons the people of Peterborough are “moving away from viewing Brexit as the most salient issue”. That may well be true – it’s impossible for me, a Londoner visiting for the afternoon, to tell – but what was most striking on Saturday in Peterborough was seeing the Brexit Party out in force. Their many activists were emblazoned with almost comically huge rosettes, unmissable compared to our well-designed but comparatively modest stickers. And the bright blue canvassers were everywhere, particularly at the train station later in the day. One woman who stopped us to ask for directions said she had come up from Brentwood, Essex, to canvass for Nigel Farage’s ‘secret millionaire’ candidate Mike Greene.

Labour’s core vote is holding up well in Peterborough, or so the canvassing data shows. But the Brexit Party came way ahead of any other party at the European elections in this very marginal seat, with 39% of the vote, while Labour was far behind in second place on 17% and the Liberal Democrats were a close third. In terms of the winning narrative, it seems likely that voters – confronted with massive Brexit Party presence – will have struggled to focus on local issues and Tory austerity during the campaign. It wouldn’t be surprising at all if the UK elected its first Brexit Party MP this week. As ever for Labour, turnout will be crucial in this by-election. If you want to help avoid that outcome, know that assisting with the GOTV operation could make all the difference tomorrow.