French Polynesia's Tahoeraa Huiraatira Party says it will formally oppose the French reform plan for the territory which is likely to be adopted in Paris under urgency by early next month.
The reform involves shortening the five-year term of the current assembly and fresh elections in two rounds of voting in January in a bid to increase political stability.
A Tahoeraa assembly member, Armelle Merceron, says the project is a step back and could see the territory lose some its powers.
She says her party is opposed to the low threshold for parties to qualify for the second round of the election which she says should not be held before May.
The ruling Union For Democracy is also set to formally oppose the changes when the French Polynesian assembly concludes its consultation.
The reform excludes provisions to ban party hopping which resulted in four no confidence motions succeeding in the past three years.