New Zealand First has officially selected Shane Jones as its Northland candidate.

Jones, a Cabinet Minister, has previously said he was gunning for the selection, and the party has officially selected him today at a meeting in Kerikeri.

Northland is considered the party's best chance to win an electorate seat, which will be of vital importance to the party if it fails to pass the 5 per cent threshold in September's election.

Jones said in a statement it was a privilege to be selected - and took a shot at the National Party.

"I will deliver an exciting policy vision for Northland, my home, with passion," he said in a statement.

"We look forward to telling our story of continued Government investment into rail, water storage, roads, digital connectivity, tourism and health after nine years of neglect by the last National Government."

The National Party's current policy is that it won't work with NZ First after the election, but party leader Todd Muller has left the door ajar for that to be possibly overturned.

NZ First party leader Winston Peters, who was also at the Kerikeri meeting, said Jones would provide Northland with a strong voice.

"He has a proven track record as a zealous champion of the North and a fighter for the provinces. He has my full endorsement."

National MP Matt King holds the Northland seat, winning it off Winston Peters in 2017 with a majority of 1389 votes.

Peters had won the seat in a byelection in 2015, but the Labour candidate Willow Jean-Prime did not campaign for the candidate vote.

Prime entered Parliament on 2017 on Labour's party list.

Prime Minister Jacinda Ardern has already ruled out an agreement to help Jones win the Northland seat in this year's election.

NZ First has been vocal about its differences with Labour in recent weeks, with Peters publicly voicing his preference to a move to alert level 1 more than a week ago.

This week, Peters said NZ First had successfully pushed for a more targeted policy to help small businesses with paying commercial rents in the Covid-hit economy.

He said Labour had wanted compulsory arbitration to capture all commercial leases, but the policy when announced excluded arrangements that had already been agreed to.

Justice Minister Andrew Little said NZ First's plan to ease commercial rent pain was laughable, and Jones chimed in to say NZ First was not going to be "absorbed" by Labour.

NZ First was on 5 per cent in a UMR poll, which was revealed to corporate clients on Friday and leaked to the Herald.

The poll had Labour on 54 per cent, National on 30 per cent, and the Green Party on 4 per cent.

It was taken the week after Todd Muller rolled Simon Bridges for the National Party leadership, and had Muller on 13 per cent in the preferred PM stakes, far behind Jacinda Ardern on 65 per cent.