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".