The Greens are celebrating a spectacular win in Bristol, where it became by far the largest party, as it headed for a record number of councillors in local elections across England.
Party officials said they believed they were on track to finish with more than 800 members on more than 170 councils.
In Bristol they fell narrowly short of taking overall control, winning 34 of the 70 seats and leaving Labour trailing a distant second with 21. The Bristol Green group, which will lead the council, becomes the largest the party has had.
Carla Denyer, the co-leader of the party in England and Wales, said it was an “exciting result”, telling the Guardian: “It’s really encouraging to see so many voters are giving their confidence to the Greens. It’s also a very promising sign for the general election.”
The party picked up all 14 seats in the heart of the city, a boost to its chances of winning the Westminster seat of Bristol Central.
The Greens went into the Bristol election as the biggest party with 24 seats but not ruling because Labour’s directly elected mayor, Marvin Rees, was in charge. The mayoral post was scrapped, however, clearing the way for the Greens to fight for a place running the city.
The party’s campaign in Bristol was marred after the government’s antisemitism adviser, Lord Mann, raised concerns about posts by two of its candidates. Both won seats.
Denyer said: “As soon as we were made aware of those issues we spoke to the candidates and took the actions we needed. The posts weren’t in line with Green party values.
“We’ve always been really clear to condemn the Hamas attacks. I’m satisfied it’s dealt with.”
Asked if the party’s strong stance on a Gaza ceasefire had won over voters, Denyer said: “A lot of people are thinking about who they trust to make decisions on a local level about providing essential local services. But there is no doubt our stance on national and international issues also affected how people chose to vote.
“We had a lot of voters bringing up Labour’s disappointing positions on Gaza and the £28bn climate change investment.”
Denyer said that, unlike Labour, the Greens would be willing to work with other parties in the city. “Cross-party cooperation is woven into Green party principles,” she said.
Elsewhere, the party was delighted to win first seats on councils including Newcastle upon Tyne, Sefton in Merseyside, Redditch in Worcestershire, and South Norfolk. It became the largest party on Hastings borough council, moving up from fourth place to first.
Adrian Ramsay, the party’s other co-leader, said: “We’ve had a really encouraging set of results, building on what we’ve seen over the last four sets of local elections where we have gained record numbers of Green councillors each time.”
He said the party was glad to have won seats in places such as South Tyneside, Exeter, Peterborough and Colchester. “That spread of seats, winning seats from Labour and from the Conservatives in rural areas and in urban areas, really shows the depth and breadth of support the Green party has.”
Asked why he thought the party was breaking through in places such as Newcastle, Ramsay said: “People are looking for a change and looking for a positive change, looking for councillors who represent them well on local issues, and what we’ve shown up and down the country is the practical impacts that Green councillors can make in being an advocate for their communities on everything from protecting green spaces to defending public services to pressing for more council housing.
“These are things that matter to people right around the country and increasingly Greens have a strong track record of winning seats in local government, being strong local representatives, playing a key role in many ruling administrations.”
The Greens hope the results will increase their chances in other general election targets such as North Herefordshire and Waveney Valley in East Anglia.
The political scientist James Dennison, an expert on the Greens, said: “It looks like a great result [in the local elections]. Let’s see the number of seats but this probably means further establishment of the party at the local level and thus a basis for geographically focused Westminster campaigns. The clear Muslim shift to the Greens is another social group to add to their electoral coalition – environmentalists, protest voters, Corbynistas, [and the] economically struggling in certain historic Tory safe seats.”