The extent and pace of gains for Maori under the National Party's coalition with the Maori Party will take centre stage when political leaders address Ratana followers at the religious movement's annual celebrations near Wanganui today.

The coalition has looked increasingly strained in the last week as Maori Party leadership moved to discipline outspoken Te Tai Tokerau MP Hone Harawira who yesterday confirmed he would attend the gathering.

Maori Party co-leaders Pita Sharples and Tariana Turia - herself a Ratana morehu (church member) - will attend as part of the Government delegation with Prime Minister John Key.

A spokesman for Mr Key said the Prime Minister would speak "off the cuff" but would probably cover "the Government's aspirations for New Zealanders including Maori" and also the $2.7 million Ratana housing upgrade announced before Christmas.

Mr Key scored something of a coup at last year's Ratana gathering, one of the first major events of the political year, when he was warmly welcomed and congratulated by church hierarchy for what he had done for Maori in his short time in power.

But dissent within the coalition and the Maori Party came to the fore last week when Mr Harawira again sharply criticised the party's relationship with National, the Coastal and Marine Areas (Takutai Moana) Bill, and what he says are "anti-social" Government moves that are contrary to his party's pre-coalition philosophy.

After receiving a frosty reception at the gathering last year, Labour leader Phil Goff will try to rehabilitate his party's historical relationship with the movement.

Those ties have weakened in recent years, especially particularly after Mrs Turia left Labour to form the Maori Party in 2004.

But Mr Goff also said last week he would address issues similar to those aired by Mr Harawira when he speaks on the marae today.

Labour still has strong ties to the church. Its candidates in this year's election include Rino Tirikatene in Te Tai Tonga electorate. Mr Tirikatene's grandfather was the first Ratana Labour MP.

Labour will also field Ratana follower Soraya Peke-Mason - who is related to the church's head, Haare Meihana - against Mrs Turia in the local Te Tai Hauaru Maori seat.

Labour's Manurewa candidate Louisa Wall also has strong family connections to the church.

"It is relationships in that sense," said Mr Goff.

"But it is also about the concerns that I think will affect Maori even more than other parts of the community - the need to ensure people can raise their kids with a decent standard of living in the face of rising prices."

Mr Goff said he would also address Maori unemployment, which is about twice the rate of the national level and is particularly high among younger Maori.

Green party co-leader MP Metiria Turei will also attend the gathering tomorrow.

Thousands of visitors descend on the Ratana village 20km south of Wanganui over several days each year to celebrate the 1873 birth of the church's founder Tahupotiki Wiremu Ratana.

According the last census there are about 50,000 Ratana followers throughout New Zealand. Organisers expect anywhere between 2000 and 10,000 people at the gathering.