The Vanuatu opposition has deposited a motion of no confidence against prime minister, Moana Carcasses.
The opposition is yet to give a reason for the move.
The motion has been signed by nine members but will need the support of 27 to be successful.
The opposition, which has 17 members, says the motion was proposed by government MPs who disagree with Mr Carcasses, but didn't name them.
If the speaker decides that the motion is in order, it will be debated on Tuesday.