The Prime Minister says he doesn't think the voting age should be reduced to 16.

His comments come after revived calls last week to reduce the voting age from 18 years.

But Bill English said increasing voter turnout is the priority, adding it's a privilege to vote and the turnout in the 18- to 25 year-old age bracket is low.

The Prime Minister also said on Mike Hosking Breakfast this morning that the Maori King's latest endorsement will be a problem for the Labour Party.

King Tuheitia has endorsed tribal leader Rahui Papa for the Maori Party to stand in the Hauraki-Waikato seat.

English said Labour has taken the Maori vote for granted and it will have to take a lot of time to shore it up ahead of the general election in September.