The Governor of Papua New Guinea's Enga Province, Sir Peter Ipatas, is the latest senior Mp to defect to the Opposition.
The group plans to move a motion of no confidence to topple Prime Minister, Peter O'neill, which could happen as soon as tomorrow.
Dozens of MP's have set up camp at a Port Moresby hotel ahead of the vote and James Marape has been nominated as their alternative Prime Minister.
Both the government and the opposition claim they have the numbers to form a government.
Arriving at the Opposition's Laguna Hotel, Sir Peter says his patience had run thin with Mr O'neill.
He says he has warned the government by talking to the Prime Minister for many years about allowing the processes and systems to work.
Sir Peter says it has fallen on deaf ears and he believes it is not in the best interest of PNG.
Meanwhile, PNG's Finance minister has reaffirmed his support for Prime Minister, Peter O'neill.