The vice-president of French Polynesia, Nuihau Laurey, has accused the Tahoeraa Huiraatira Party of using double standards by expelling him.
The party's leader, Gaston Flosse, removed him and three others for wanting to stand in next month's elections to the French Senate in defiance of the party's earlier nomination of two candidates.
Mr Laurey has told the Tahiti-infos website that in the municipal election, the Tahoeraa accepted that rival candidates stood under the party banner.
He is standing with an assembly member, Lana Tetuanui, who have jointly launched their bid despite a reported party offer that their expulsion would be rescinded if they withdrew their candidacy by tonight.
The Tahoeraa has 38 of the assembly's 57 seats, but its assembly group is now poised to splinter into two, with one siding with the government and one siding with Flosse.
Flosse is banned from political office because of last year's conviction for corruption but he has retained the party leadership.