The Green party’s candidate for the Makerfield byelection has withdrawn from the ballot less than 12 hours after being announced.

Chris Kennedy was announced to be running in the seat for the Greens on Thursday morning, but nine hours later the party said he had dropped out, citing “personal and family reasons”.

The Times reported it had approached Kennedy about a series of social media posts he had shared about an attack on Jewish ambulances in north London in April. An Instagram video shared by Kennedy described the arrests of two men over the incident as “total bullshit to keep the false flag flying”, the paper reported.

He also reportedly shared a post by a user named Hugh Anthony, a self-described “proud ethno-nationalist”, which said the response to the Golders Green arson attack in March made “no sense”.

A Green party spokesperson said: “These posts don’t reflect the views of the Green party. We have spoken to Chris about these posts, and he has now deleted them. He apologises for the offence caused.”Kennedy was chosen by local party members. According to the Times, the frontrunner had been Hayley Pierce, a portrait artist, but her prospects seemed to have been damaged by social media posts which the newspaper published.

Later on Thursday, the Green party said Kennedy, a nurse and children’s safeguarding specialist, had withdrawn for family reasons. “We wish Chris the best and understand that family has to come first,” the Greens said.

“As a party, we are reopening nominations now because we believe people in Makerfield deserve a real choice at this byelection, and the Green party will be standing to offer exactly that.

“Across the country, more and more voters are turning away from the old parties and looking for politicians who will genuinely stand up for their communities. We will also be redoubling our efforts on campaigning to expose the risk of Reform, a party who seeks to divide our communities.

“This election has to be about how to make the super-rich pay their fair share, how we tackle the cost-of-living crisis with lower bills and affordable housing, and how we protect our public services and our green spaces.

“It has to be about offering Makerfield hope over hate.”

Nominations for a replacement candidate will reopen on Friday and a selection meeting is planned for Monday evening.

Some party members are reportedly wary of being blamed for splitting the progressive vote and allowing Reform to win in Makerfield. One senior party figure told the FT: “We do not want this one to go to Reform, and to be quite frank, we do not want Labour to turn around and say, ‘If you vote Green, you’re actually voting Reform’, because that will be used for the next three years.”

It follows a report in the Guardian that revealed the Greens were locked in a “very civilised” internal debate about how to challenge Burnham.