Reform UK is examining whether sexist comments by its candidate in the Makerfield byelection may have harmed the party’s chances, after Nigel Farage accepted the result had disappointed him.

The party’s examination of its defeat comes after Andy Burnham won 55% of the vote share in a poll that Reform hoped would be a tightly fought battle between the Labour leadership hopeful and its own candidate, Robert Kenyon, a local plumber.

Canvassers from different parties reported that voters highlighted sexist and lewd social media posts by Kenyon, which emerged during the campaign, with women in particular saying they were put off by them.

After Kenyon came more than 9,000 votes behind Burnham in Thursday’s vote, one Reform activist said the party had advised the candidate not to apologise for the comments. “That’s something that was not his fault, it was how he was advised,” they said.

The issue rose to prominence when the TV presenter Carol Vorderman used a video posted online to demand an apology from Kenyon, after it emerged he had joined in a graphic discussion about her, in since-deleted posts.

“I will admit that the Vorderman stuff did not help us,” another Reform source said.

Farage’s party has pointed to the scale of the task it faced taking on as well-known a figure as Burnham, even in a seat demographically more favourable to Reform than Labour, saying Kenyon performed well to increase his share of the vote from 2024, even by just 2.7 percentage points.

The party was also slightly buoyed by Rupert Lowe’s far-right Restore UK taking just under 7% of the vote, less than some forecasts had predicted.

In a video message posted on X on Friday morning, Farage urged people who voted for Restore to back Reform instead, saying it was the only viable contender on the right of UK politics.

The result had been “a dramatic, emphatic win for Andy Burnham”, Farage said in the message.

Reform had hoped to win at least 18,000 votes, against the 15,696 it achieved, Farage said, arguing that his party had been “slightly hoist with our own petard” in taking on a Labour challenger whose implicit message had been that a vote for him was a vote to remove Keir Starmer, which was Reform’s slogan in May’s local election.

Burnham’s personal standing in Greater Manchester, where he has been mayor since 2017, appeared to be more of a factor, as well as the comments by Kenyon, who did not apologise but sought to present them as showing he was an ordinary person rather than a professional politician.

Despite Restore’s modest showing, Farage will be concerned to have lost some votes to a party whose talk of mass deportations and at times openly racist rhetoric has seemingly nudged Reform into taking a more hard-right and nativist approach in recent weeks.

Farage addressed those who voted Restore in his message: “I would say directly to them: what do you want? We are the challenger party to the left in this country, and I would urge you to think again, I really, really would.”

Reform was, he insisted, “still the big national party on the centre right”, saying that despite the Conservative win in the Aberdeen South byelection, also held on Thursday, Kemi Badenoch’s party remained uncompetitive in large parts of the UK.

He ended his message: “A disappointing morning, but we keep going.”

Faced with the threat from Restore Britain, a predominantly online phenomenon, where Lowe’s anti-immigrant messages have been amplified by Elon Musk, the owner of X, who supports Restore, Farage has started pushing Reform on to more hard-right turf.

In the wake of the case of Henry Nowak, the student who was handcuffed by police as he lay dying from a stab wound after his killer told officers Nowak had assaulted him in a racist attack, Farage has argued repeatedly that white people in the UK face the most racism in what he calls a “two-tier state”.

Reform’s migration policy has also become more hardline, and now also targets EU nationals with settled status, some of whom have lived in the UK for decades.

Under planned Reform policies, EU nationals would be among people barred from living in social housing, and employing them would become notably more expensive for companies.