The contents of the chat, which were leaked to the Daily Post newspaper, implicate MPs planning to remove the Leaders Party of Vanuatu from the ruling coalition.
The newspaper said the chat implicated eight MPs, parliamentary secretaries and ministers from four of the coalition's parties.
None of them seem to be acting with the knowledge or consent of their leaders.
But it showed discontent at the Leaders Party's decision to stand a candidate, Jimmy Nipo, in the Tanna by-election for the seat of former deputy prime minister Joe Natuman.
The members suggested a fear of what they view as the growing strength of the Leaders Party, and calls for moves to cut it from the coalition.
The coalition was formed following the 2016 election and has - so far - managed to avoid the infighting, factions and defections that have seen so many of Vanuatu's governments dissolve mid-term.