Zack Polanski has said he will not overturn a motion passed by Green Party members that declared Zionism a form of racism.

The Green leader told Sunday with Laura Kuenssberg that, while he would like to make amendments, it would be party policy until 2028.

The motion, passed at the party’s conference earlier this month, described Zionism as an ideology supporting “an ethnonationalist Jewish state in historic Palestine to the exclusion and/or domination of the non-Jewish population”.

It divided the party and sparked a major backlash from MPs, Jewish campaigners, the government and the European Green movement, with the equality watchdog writing to the party for more information on it.

The fallout from the motion overshadowed the final days of Polanski’s campaign in the Holborn and St Pancras by-election, in which he came second to Labour, and threatened his leadership.

He came under criticism for not voting on the motion which was passed by 1,022 votes to 813 – a small fraction of the party’s 230,000 members – in Brighton earlier this month.

The motion also asserted the party’s backing for “a single democratic state throughout historic Palestine”, a full arms embargo on Israel and a commitment to Palestinian liberation.

Asked if he would now step in as leader to overturn it, Polanski said: “I’m not going to try to overturn it.

“At the first available opportunity, I do want to amend it – I want to move away from one state, towards saying that Israelis and Palestinians should decide that future for themselves.”

He said this would not be until 2028 as “you can’t [amend it] within the rules, so when you vote on something in our party conference that’s then policy for two years”.

Kuenssberg asked if he would therefore change the rules as leader, but Polanski said: “I think if members have made a decision, then I respect the democratic will of our members.”

Polanski had previously said he would not have voted for the motion without two amendments.

The first of these would have avoided “determining there was a single democratic state”, and the other would have specified that the motion should not be used to discipline Jewish Green members who attend synagogues that consider themselves Zionist.

Both of these amendments were voted down by members at the party’s conference.

Green MPs, including Ellie Chowns, have called for the party’s member-led decision-making procedures to be reviewed given how few people took part in the vote.

Asked if he thought Zionism was racist, Polanski said did not think this was controversial, adding: “I think what’s controversial is that 75,000 Palestinians have been murdered in the last few years.”

He said they were “being murdered because they’re Palestinian” and said that was “very obviously a racist ideology”.

Kuenssberg asked Polanski if he accepted that for many Jewish people, Zionism was the right to have a safe place to live, or homeland.

“I think that’s what people think it means, but actually in practical application – which is what we’re talking about here – that homeland has come to the cost of the Palestinian people,” Polanski, who is Jewish, said.

“I want equal rights for Israelis and Palestinians – the practical application of Zionism has not resulted in that.”

He reiterated that no Jewish Green members would be excluded based on their faith or background.

He also said being Jewish and supporting Israel were “two separate things”.

Polanski’s latest comments come after a fortnight of criticism from across the political spectrum over the motion.

On Thursday, the Equality and Human Rights Commission (EHRC) wrote to the party asking for more information about the motion and its practical effects.

The regulator said “many Jewish people will be feeling vulnerable”, but said it needed more details to assess if any parts of it could be considered discriminatory under the 2010 Equality Act, after a letter from dozens of Labour and Lib Dem MPs.

Labour has said it will end power-sharing agreements with the Greens on local councils, unless its councillors disown the motion. Polanski said it was up to Green councillors to do what they saw fit.

The motion’s author, Green Party member Lubna Speitan, said this week that the Labour government had been a “participant in genocide” and had “no moral high ground to talk to us about antisemitism, racism or any other matter”.

The International Court of Justice is currently hearing a case that accuses Israeli forces of genocide. Israel has said the accusations are “wholly unfounded” and based on “biased and false claims”.

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