The Langafonua Tu'uloa Party in Tonga is calling on the Prime Minister and three other cabinet ministers to step down.
The party says the four have breached a public proclamation made in 2004 and that their term in office has expired.
It says their appointment in 2005, by the late king, Taufa'ahau Tupou IV, was meant to be no longer than the period for which they were elected to Parliament, which was three years.
The Tonga Secretary of Langafonua Tu'uloa, Robert Tofa, says the party wants to bring some certainty to government in Tonga.
"The whole issue is of course, people in authority, government or parliamentarian, or whoever, were not following up the royal proclamation, and make sure that it didn't eventuate, as it should have done so. Hence, a lot of us feel maybe a lot of people in Government don't take royal proclamations seriously."
Robert Tofa says four new ministers should be replacing them, under the same proclamation.