Andy Burnham has called on Green leader Zack Polanski to reverse a motion passed by members of his party declaring Zionism a form of racism.
The prime minister said the motion, approved on Sunday at the party’s conference in Brighton, was “completely wrong” and showed “terrible judgement”.
The motion defined Zionism as an ideology supporting “an ethnonationalist Jewish state” and backed a “single democratic Palestinian state in all of historic Palestine”, which includes modern-day Israel.
In the wake of the vote, Polanski has said he would not accept anyone being excluded from the Green Party “because of the religious or communal body they are part of”.
The Green leader has declined media interviews since the motion was passed and did not answer questions from a BBC reporter about the motion ahead of Burnham’s comments.
It comes as polls close in Thursday’s Holborn and St Pancras by-election, in which Polanski is a candidate.
The motion has complicated the final days of Polanksi’s campaign in the contest, where the Greens have been looking to overturn a substantial Labour majority in the seat vacated by former Prime Minister Sir Keir Starmer.
It has sparked days of controversy, with four of the five Green MPs opposing it, its co-deputy leaders split on supporting it, the Green deputy leader in Wales resigning, and condemnation from members and Green counterparts in Europe.
Polanski did not vote on the Zionism motion, having left the conference early to return to London for the by-election campaign.
An amendment he had backed to specify that the motion should not be used to discipline Jewish members attending synagogues that consider themselves Zionist was voted down by members.
Before the vote, he had also said he wanted to see the reference to a single Palestinian state changed, arguing: “I don’t believe we as a Green Party of England and Wales, or even the British government, should be deciding what the future settlement looks like.”
The Green Party has an internal democracy model, under which official party policy is decided by members. However, these positions are not necessarily included in the party’s general election manifestos.