The president of Vanuatu's Labour Party, Joshua Kalsakau, has formally withdrawn the party from the government coalition.
This comes after the prime minister last week reshuffled his cabinet, dropping the Labour Party's Yoan Simon as justice minister.
Mr Kilman reportedly made the move because he believed Mr Simon had signed a motion for a vote of no confidence against him.
But Mr Kalsakau says that wasn't the case at the time, but all three Labour MPs have now signed it.
He says he's surprised that the prime minister, as a former police chief, had based his decision on rumour rather than firm evidence.
Mr Kalsakau says the motion against Mr Kilman is likely to go to the speaker, Maxime Carlot Korman, on Friday.