Hone Harawira's indefinite suspension from the Maori Party caucus is a necessary step. It is also one made with a high degree of self-interest and expediency on the part of his prosecutors.

And it only makes political sense if Harawira's expulsion from the party as a whole soon follows.

His suspension is a necessary minimum because - as the party's co-leaders Tariana Turia and Pita Sharples assert - no political movement can survive when it is constantly divided within itself.

But it is also an expedient move because he is fast undermining their control of the party.

Harawira is not a maverick even though he is frequently labelled as such. He is not a Chris Carter, a Brian Connell or a John Tamihere, all of whom slipped out of favour for reasons which had little to do with their parties' policy direction.

Harawira is a true rebel. With his continual questioning of the party's direction and its alliance with National, he is the acknowledged leader of a sizeable faction that is now in a power struggle with the ageing leadership over the party's future.

His expulsion would not end dissent within the party, but it would remove the person who provides a media focus.

Harawira's mistake has been to give the leadership all the reasons it needed to justify his suspension. His provocative behaviour towards Sharples at Waitangi at the weekend was the final straw.

The big question now is whether the party's disciplinary committee will recommend his expulsion when it meets later in the week.

Booting Harawira out of the parliamentary wing, but not the wider party, could allow him to remain a thorn in Turia's and Sharples' sides throughout election year. The party would be in perpetual crisis.

If he is not expelled now, suspension from the caucus at least puts him firmly on notice of that likelihood unless he starts toeing the line.

His angry reaction to his suspension suggests the latter is unlikely, however. His exit thus looks inevitable.

To convince Maori voters it had little choice but to suspend him, the leadership is running the line that the party is always bigger than the man.

True. Barring the case of Winston Peters, who is New Zealand First, things cannot be any other way. A party's MPs must hang together. Otherwise - to borrow from Benjamin Franklin - they will most assuredly end up hanging separately.

Minor political parties become dysfunctional if some of their MPs claim credit for policy achievements but refuse to take responsibility for unpopular decisions or compromises the party is forced to stomach as the price for getting those achievements.

Such rebel behaviour first embarrasses then undermines the party's leadership. Party discipline starts to weaken. Things get increasingly hazy as to what the party actually stands for. It becomes increasingly difficult for the voter to have confidence in the party's ability to follow through on its manifesto promises.

Turia and Sharples say Harawira's suspension is the outcome of behaviour stretching back over the past five years. That amounts to the whole time that the Maori Party has been in Parliament.

That assertion is an attempt to persuade those siding with him that he is not being punished solely for the fall-out over his objections to the Maori Party's backing of National's solution for the foreshore and seabed farrago.

But it begs the question of why it has taken the caucus so long to discipline him. It adds weight to the theory that he is only being hauled into line now because only now is he in a position to potentially blow the whole party asunder.