Vanuatu Prime Minister Sato Kilman's government claims to have the backing of 27 of parliament's 52 members as a motion of no confidence is to be debated.
The two political groupings have set up camp in separate locations to ensure no-one defects.
A motion was voted on last month which the speaker interpreted as the government's ouster but which the court of appeal overturned.
There have been suggestions that elections be held a year early in a bid to end the instability.
Meanwhile, Richard Kaltongga, a spokesperson for Vanuatu's Prime Minister, is accusing the previous government of Serge Vohor of making unlawful payments to staff during its brief period in office.
"The recent government of Serge Vohor, regardless of the fact that the court declared that government unconstitutional and unlawful they still went ahead and paid out their gratuities and made payments to their staff, which is not proper and the government is going to look at ways to recover those moneys that have been paid out unlawfully."