Labour will bring in a new way of selecting its leader today by allowing party members to vote - and it is expected to water down a proposal that would have made it hard to mount a coup against an incumbent leader.

The party conference opened last night, and it is crediting the record attendance to significant reforms due to be voted on today, including giving party members and unions the power to vote for the leader.

Leader David Shearer will give his first conference address tomorrow and try to silence his critics, who have called on him to stand down after less than a year in the job. He is also expected to make a policy announcement on affordable housing.

The conference opened with speeches from Auckland Mayor Len Brown - who also addressed National's annual conference this year - and outgoing Equal Opportunities Commissioner Judy McGregor.


But the main focus is the reforms the party will vote on today, including the change to leadership elections. That change will give party members 40 per cent of the vote on the leader in future contests - the same as the caucus. Affiliated unions will have 20 per cent. However, only the caucus can force a leadership contest.

The team that undertook the review initially proposed allowing a post-election confidence vote on the leader and at other times requiring two-thirds of the caucus to sign a petition to force a challenge.

That would have given the incumbent a high level of protection.

But party members are expected to vote for a lower threshold of 50 to 55 per cent, making it much easier to overthrow a leader.

Party secretary Tim Barnett said he did not expect it to result in instability or a high churn rate of leaders. He doubted members and affiliated unions would club together to force through a leader who was widely disliked by caucus.

That was considered an issue in the last leadership contest when David Cunliffe was seen by members as being the favoured candidate.

It was a similar system to that used by the British Labour Party "and they haven't had instability", said Mr Barnett.

He said the review team and Labour's council had also considered allowing members to force a confidence vote in the leader, but decided against it. However, it was possible the rules could change over time.


Mr Barnett said about 620 delegates were attending the conference - 20 per cent more than at its election-year congress and the highest since 1989, when there were rifts in the party after Rogernomics.

"But that no longer applies. Peace has broken out," Mr Barnett said.

The changes will also require leadership contestants to run an open campaign for the job, similar to the United States primaries. It is expected members will be able to vote at meetings or by postal ballot.

There was a partial dummy run last year, when David Shearer and David Cunliffe travelled the country to address party members before caucus voted - and the party noted an increase in party members.

Mr Shearer faces his first confidence vote in February. He would not comment on the proposed changes, saying he was comfortable with whatever the party decided.

He said the other changes were "long overdue" and would improve Labour's campaign organisation at the grassroots - something the party had traditionally excelled at but which had weakened in the past few years.

There is an event today that clashes with the conference - former Labour MP Stuart Nash is getting married, forcing some to choose between the two.

Annette King and Shane Jones are the only MPs expected to attend, and Ms King will return to the conference early that evening to prepare for Mr Shearer's policy announcement the next day. That is expected to be on affordable housing, which is in Ms King's portfolio.