The Green leader wants executives to hold greater control over policy direction after a conference resolution triggered fierce internal revolt.
Senior figures call for constitutional reform after just 1,022 conference votes defined Zionism as racism and backed a single Palestinian state.
Brighton & Hove City Council's leader accused the party of a dereliction of duty after its members voted on a motion equating Zionism with racism.
The party faces warnings of high-profile resignations as members prepare to debate a highly divisive motion.
