Vanuatu's Prime Minister Ham Lini is under pressure to replace the Minister for Internal Affairs.
This follows the decision by the Minister, George Wells, to defect from the Vanuaaku Pati to another government coalition party, Mr Lini's National United Party, or NUP.
Mr Wells says instability within the VP caused by continued opposition to his position in the party, and as Minister, is behind his defection.
However, a provision in the MOU which binds the coalition government stipulates that the Minister for Internal Affairs must be a VP member.
The VP leader and senior government minister, Edward Natapei, says while he is sad to see Mr Wells leave, the party wants to retain the portfolio.
"It's up to the Prime Minister now to decide what he wants to do but we are, on behalf of the Vanuaaku Pati, going to be asking him [Mr Lini] to terminate him [Mr Wells] from the ministry and to appoint a member of the Vanuaaku Pati into the cabinet."