Jean Paul Virelala, Jimmy Andeng, Anatole Hymak and Russell Nari said they founded 'Vanuatu First' and Mr Korman had no mandate and should not have gone public while the party was still working on its structure.
Mr Virelala said Mr Korman was invited to their meeting as a sign of respect because he is one of the veteran political leaders who took the country away from colonialism.
But he said the group is still working on an executive committee to elect the president of the party.
The group said it has expelled Mr Korman and banned him from contesting the 2020 national elections under the party ticket.
However the Daily Post newspaper reports Mr Korman saying he was elected the interim President and the four men have no right to expel him so he is still the interim head.