The Vanuatu parliament will meet next Monday to elect a speaker and new prime minister, with one grouping saying they can form a new government.
The summons from the clerk of Parliament comes as a coalition built around the National United Party claims it has signed a memorandum of agreement among five parties, giving it 28 seats in the 52-seat parliament.
The other four parties are the Vanuaaku Party, the People's Progressive Party, the National Cultural Party and the People's Action Party.
The Union of Moderate Parties has also claimed it can form a coalition.
