Zack Polanski is now the most unpopular of the nationโ€™s main party leaders as he fights to stay in the top post following his failure to win Sir Keir Starmerโ€™s former constituency for the Greens. New polling by Opinium shows the Greens are the most likely to be seen as having an โ€œantisemitism problemโ€ (+18) with more than half of its supporters approving of a conference vote which declared it an โ€œanti-Zionistโ€ party. Mr Polanski now has a net popularity rating of -29, a seven point fall which comes as he insists he will continue to lead the controversy-ensnared Greens.

Israelโ€™s foreign ministry announced Mr Polanski, who is Jewish, was banned from entering the country after the party passed a motion declaring Zionism a form of racism by 1,022 votes to 813. Mr Polanski went on to lose Thursdayโ€™s Holborn and St Pancras by-election, with Labourโ€™s Sagal Abdi-Wali winning a majority of 3,364. Fifty-six percent of current Green voters think the party was right to pass the anti-Zionism motion, with only 13% saying they were wrong. Among the wider public, 35% think the Greens were wrong to pass the motion with just 16% saying they were right to do so; 16% think they were neither right nor wrong and 33% do not know.

Opinium found more than two in five (46%) UK adults think the anti-Zionism motion is the wrong priority for the Green Party to focus on, with only 11% saying it is the right one. One in three stated that the decision to pass the motion made them less favourable towards the Greens, with just 10% saying it made them more favourable.

Labour held onto the top place when people were asked which party they planned to vote for in a general election on 29% (-1); Reform is second place on 23% (-2) with the Conservatives on 20% (+3); the Greens are on 9% (-2), tying with the Liberal Democrats (no change). Worryingly for the Greens, when people were asked whether they would ever consider voting for the main five parties, they had the worst net negative score (-42). Labour performed best but still had a negative rating (-15), ahead of the Conservatives (-23) and Reform and the Lib Dems (both on -32).

Conservative leader Kemi Badenoch will be encouraged that half the public support her plan, announced at the party conference in Birmingham on Wednesday, to exempt family homes from inheritance tax. Just 16% oppose it. Nearly one in three people (32%) think her conference speech was good, while 14% say it was bad โ€“ but 54% have no opinion.

When it came to how the public judged Tory polices, they scored most highly on defence and national security (+9), crime, justice and prisons (+3) and welfare and getting people into work (+2). They scored worst on Brexit and Britainโ€™s relationship with the EU (-7), energy and climate change (-5), and public services (-3).

Prime Minister Andy Burnham is the only party leader with a net positive approval rating (+8) while Mrs Badenoch is on net zero. Reform UK leader Nigel Farage’s rating was net -26 (-4).

James Crouch, head of policy and public affairs at Opinium, said: โ€œTogether, the two main parties now have their highest combined share in almost two years. The question is whether this is as good as it gets for the old guard, or the beginning of a genuine trend.โ€

A Green Party spokesperson said: โ€œIn Holborn and St Pancras, Zack tripled our vote share, adding [22.4 percentage points], and turned what has been a safe Labour seat for over four decades into a marginal.โ€