The president of the Cook Islands Democratic party says the prime minister, Dr Robert Woonton, has no right to form a coalition with the opposition Cook Islands party.
Makiuti Tongia says the party constitution prevents Dr Woonton from making the decision on his own to join forces with another party.
And, Mr Tongia says there are only the two Democratic party MPs joining the nine CIP MPs which would leave the coalition short of a majority in the 24 seat parliament.
He says the Democratic party caucus is opposed to Dr Woonton's move.
"The rest are standing solid behind us and negotiations are still ongoing with the team to stay put, to stay solid. Some members of the CIP, the Cook Islands Party are not happy with the decision by two people to form a coalition. The Cook Islands party executive is divided on this issue."
Mr Tongia says the deputy prime minister, Ngamau Munokoa, has already resigned from Dr Woonton's administration and several ministers say they will follow suit.
He says the Democratic party has the numbers to form the next government and disaffected CIP members will support them on supply and confidence issues.