The Green Party is to ballot its members in November about whether it should have a single leader, rather than its "principal speakers" formula.
Sian Berry and Derek Wall are the party's current principal speakers
Traditionally the Greens have avoided a figurehead, instead having co-speakers.
But London Assembly member Darren Johnson, who backs a change, called the current system a "ridiculous barrier" to getting the party's message across.
Current co-leader Derek Wall opposes the change, warning against getting "sucked in" to an "ego-led" system.
At the Greens' annual conference in Swansea, members voted in favour of a ballot of all 7,000 members on whether they should create a leader and deputy - or whether they should stick with their two principal speakers.
The ballot will be held in November 2007, following a "full debate" at the next conference in Liverpool in September.
Among those in favour of the idea is London Assembly member - and former mayoral candidate - Darren Johnson.
He told the BBC News website: "The Green Party has had two national speakers for many years now, many members have felt that this has hampered our ability to get our message across and really have some identifiable, key figures in the party."
He said he could understand concerns of some about a "Thatcher or Blair style figure who totally dominates the party" and stifles debate, but he said that would not be the model that was being proposed.
He said he had waited "20 years" for the debate, but said it had come to a head because "climate change is becoming even more serious and the need to catapult the Green Party into the mainstream of British politics".
He added that not having a leader was "just a ridiculous barrier in terms of getting our really important message across".
But Mr Wall, who last week told the conference that the party should not get "sucked in" to having a figurehead like other parties and said "ego-led" political figures had the potential to corrupt.
He told the BBC: "If you are a clear speaker, there's no problem getting coverage and explaining the party's views."
He said other European Green parties who had adopted a leader had become less radical, partly as a result.
While all political parties started off as being participatory, in the end members just became "puppets" he said, once a party leader was involved.