Andy Burnham is facing calls to rule out any potential coalition deal between Labour and the Green Party after it voted to adopt a policy defining Zionism as racism.
The move, which has prompted questions over the direction of the party and the future of Zack Polanski as leader, has been widely condemned, with the chair of Jewish Greens saying she was considering leaving the party while the chief rabbi, Sir Ephraim Mirvis, warned the move was a "threat to British Jews and to Britain".
Leading barrister Adam Wagner KC also said there was a strong risk the motion, passed at the Greens’ annual conference this weekend, contravenes the Equality Act 2010.
The row erupted just days before Mr Polanski attempts to become an MP in a crunch by-election in Holborn and St Pancras, after the seat was vacated by Sir Keir Starmer.
The Green Party leader attempted to draw a line under the controversy, liking a social media post telling people who oppose the motion to “get over yourselves and move on” because “sometimes they don’t go your way”.
But Adam Langleben, the former national secretary of Jewish Labour Movement and now director of the Progress think tank, told the Independent: “Yesterday’s actions should disqualify them from holding major public office. Labour should rule out joining any kind of coalition with the Greens”.
Ben Judah, who advised David Lammy at the Foreign Office until earlier this summer, also told The Independent: “Labour should not countenance forming a coalition with the Green Party as long as this remains their policy.”
Paul Ovenden, Keir Starmer’s former director of strategy in No 10, said: “This should be a moment of reflection for those around the Labour Party who think a pact with the Greens is the path to progressivism. Not only would it be morally wrong, it would be electorally wrongheaded. ‘vote Labour, get the cranks’ - a sort of steroid-enhanced version of the 2019 election - would be a devastating opposition attack in the many Labour-Tory battlegrounds that will make up the next election. There is little to be gained for Labour from flirting with the new, extreme Green Party but there is much to lose.”
Labour MP Luke Akehurst said: "I hope the electorate will react by pushing them into political oblivion, but it also needs to be clear that there are no circumstances where Labour can share power with a party professing an ideology that breaches the IHRA definition of antisemitism."
Another Labour MP told The Independent: “No one should be contemplating it (a coalition) unless the Greens urgently revise their position.”
Mr Wagner also said it was his opinion that “there is a strong risk that the motion as passed contravenes the Equality Act 2010, which applies to political parties, as it will discriminate against and harass people who hold Zionist beliefs and Jewish people more generally.”
He added: “The motion describes the Green Party as “anti-Zionist” and says "Zionism, as defined above, will be treated as any other form of racism”.
“There is a strong risk that this would be found by a court, and the EHRC, to directly discriminate against people who hold the protected belief of Zionism (belief discrimination), and also will indirectly discriminate against Jewish people who might want to join or are already members, and who hold Zionist beliefs (racial discrimination).
“There is also a strong risk that this policy, especially if it is implemented through disciplinary complaints and determinations, will create an intimidating, hostile, degrading, humiliating, or offensive environment for Jewish people, therefore harassing them.”
Meanwhile, as the row gathered steam, the chair of Amnesty International, Sandy Ruthven, has left the Greens, telling the Jewish Chronicle the party was “failing to confront prejudice” in its rank.
Rabbi Charley Baginsky, co-lead of the Movement for Progressive Judaism, also told Times Radio that the ‘Zionism is racism’ motion is itself “a racist policy”.
Earlier, the chair of Jewish Greens Vivien Lichtenstein said she had not decided whether to remain a member, saying the motion risks UK Jewish organisations, including joint Arab-Jewish organisations, being labelled racist.
Mr Polanski, who did not vote, has been barred from entering Israel in retaliation for the motion.
The motion declares the Greens to be an “anti-Zionist party” and sets into its policy that Zionism, the movement to develop and protect a Jewish state in Israel, will be “treated as any other form of racism”.
It also supports the establishment of a “single democratic Palestinian State in all of historic Palestine with Jerusalem as its capital”.
Supporters chanted “say it loud, say it clear, Zionists are not welcome here” as the campaigners behind the motion, Greens for Palestine, gathered to speak to the media.
Asked if the new stance meant Zionists would be kicked out of the party, former councillor Salma Yaqoob said “absolutely not”.
But chief rabbi Sir Ephraim Mirvis has condemned said he was "appalled" by the motion, and warned that the measure passed at the conference was a "threat to British Jews and to Britain".
Israel accused the Green Party of legitimising “the destruction of the State of Israel” with a “clear antisemitic text”.
In a statement with Green MPs and his deputies, Mr Polanski said there is “no conflict between supporting the rights of Palestinians and the rights of Jewish people”.
A party spokesman said: “The Green Party is an anti-racist party and has consistently opposed the illegal occupation of both Palestinian and Syrian land, called for an end to arms sales to the Israeli government and spoken out fearlessly about the devastating situation in Gaza and the West Bank.
“Those positions remain central to our approach. So too does our deeply-held commitment to equality, justice and human rights for all, and opposition to racism in all its forms.”
The members voted against adding a clause to make clear the motion should not be used to “pressure, proscribe or discipline” party members for their affiliation to synagogues or other Jewish groups that describe themselves as Zionist.
The Board of Deputies of British Jews said the Greens have become “an extremist party”.
The vote exposed divisions within the party as four of its five MPs – Ellie Chowns, Sian Berry and ex-leaders Adrian Ramsay and Carla Denyer – came out to publicly reject the motion.
Ms Chowns said in a social media post that she was concerned the motion “risks fuelling division and risks undermining the party’s ability to advocate effectively for justice and peace”.
Afterwards, party leader Mr Polanski and the five MPs released a joint statement saying they would “always uphold universal human rights”.
“We will never tolerate any form of discrimination or harassment.
“We will continue to stand in opposition to genocide, ethnic cleansing, apartheid and the illegal occupation.
“We will continue to call out the heinous crimes of the Netanyahu government.
“And we will continue to work to ensure that the Green Party is an anti-racist party in every way.
“We know there is no conflict between supporting the rights of Palestinians and the rights of Jewish people.”
The position will become party policy, but the Greens do not require all their politicians to back it.
Chair of the Labour Party Bridget Phillipson described the decision as “fundamentally wrong”, while the Conservatives said it showed the Green Party is “toxic to its core”.
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