The loss of the Leaders Party's eight MPs means the government of prime minister Charlot Salwai only has a one seat majority.
In a statement, the Leaders' Party president, Jotham Napat, said that having spent the past week speaking to members, the people have lost faith in the government.
Mr Napat and another MP, Matai Seremaiah, were last week pushed out of the government, apparently because of fears about their growing strength within the coalition.
Mr Napat said he met at the weekend with Mr Salwai, who told him their ouster was not his decision.
Parliament will next meet on 23 November, amid increasing speculation that the opposition is trying to rally a motion of no confidence.