Tonga's MPs have been debating whether non-elected members of parliament can vote in a motion of no confidence in the Prime Minister, Lord Tu'ivakano.
There is a clause in the constitution that appears to exclude those members but the government wants an interpretation of that.
Earlier, an attempt to hold an urgent vote on the motion was defeated by the government.
In its explanation for bringing the motion, the opposition Democratic Party says several matters have arisen which show the untrustworthiness of the government.
It says there have been unconstitutional actions which undermine the government's responsibility to uphold the rule of law.
Radio Tonga reports that the opposition claims the changes and the reshuffling of cabinet are signs of an unstable government, and a failure on the Prime Minister's part to bring unity.
It also says Lord Tu'ivakano has failed to lead and control Tonga's development efforts for the benefit of all the people of Tonga, and for these reasons he should step down and allow the election of a new prime minister.
When or if a vote will be held remains unclear.