One of the Union of Moderate Parties' six MPs, Tanna MP Robin Kapapa, recently formally defected to the opposition from the Bob Loughman-led government.
The party's non-parliamentary membership is urging the rest of their MPs to follow suit.
The UMP president, former prime minister Serge Vohor, called for a meeting of the party's national executive today to discuss a possible move by all its MPs
However while Vohor reportedly wants the UMP to defect, the party's parliamentary leader, deputy prime minister Ishmael Kalsakau, is opposed to the idea.