I would say the Green party association with Islamists helped the Green party to grow the way it has done under Polanski. But will ultimately lead to its downfall as a serious political party that other parties such as Labour could have formed an alliance with.
Support for the Green party has declined in recent months, and after the vote Zionism is Racism, those with more moderate views will surely not want to be associated with a party associated with antisemitism. From the Observer (dated 11th October):
Greens face ‘existential threat’ as membership plummets after anti-Zionist motion
Support for the Green party is plummeting after it lost a crucial byelection and faces accusations of antisemitism. The latest Opinium poll for The Observer puts the Greens on their lowest share of the vote since Zack Polanski became leader last year.
The party has dropped to 9 percentage points, down from 16 points in May. The proportion of young people – those aged from 18 to 34 – planning to vote Green has halved over the past five months, from 28% at the time of the local elections in May to 14% now.
Polanski’s approval rating has plunged by seven points, making him the most unpopular of the party leaders. Only 17% of voters think he is doing a good job and just 14% believe he represents what most people think. According to the poll, 42% of the electorate believe the Greens have a problem with antisemitism.
The conference vote last weekend has triggered turmoil in the Greens. Four of the party’s five MPs are at odds with members and some senior figures have called for Polanski to resign.
Insiders suggest that thousands of members have quit the party over the past week in protest at the motion. One local party has seen a two-point drop in membership since last Sunday, with similar falls reported in other areas. If this were replicated across the country, it would mean 4,400 people had resigned.
observer.co.uk/news/politics/article/greens-face-existential-threat-as-membership-plummets-after-anti-zionist-motion