Vanuatu's opposition says it does not believe that the government can push through controversial amendments to the constitution.
Its leader, Sato Kilman, says there are 19 opposition MPs in the 52-member house which will vote against the bill aimed at preventing party hopping and providing the government with a grace period.
He says a three-quarters majority is required to make the changes and even government backbenchers have indicated they won't vote for it.
Mr Kilman says he will ask the prime minister to withdraw the bill but they need to begin discussions between the two sides.
"There's really no dialogue between the caucus of the two groups, and also between the government and the opposition. I believe if we can have more meetings together, we will probably come up with something better, something I believe legal, democratic and constitutional in addressing this problem."
Mr Kilman says the bill should never have been introduced in such speed and with such secrecy.
He says they didn't know the contents of the amendments until a couple of days ago.