LATEST 5.25pm:

The Labour Party has selected the same man who ran for them at last year's general election, to represent the Party in the Northcote by-election.

Shanan Halbert trailed former Northcote MP Jonathan Coleman by 6,000 votes in 2017, but will be campaigning to beat National's new pick, Dan Bidois.

Both Labour and National's selected candidates are of Maori decent, with Mr Halbert hailing from Rongowhakaata in Gisborne, and Mr Bidois from Ngati Maniapoto in the Waikato.

The two candidates are likely to be the front-runners as the campaign for the Northcote seat kicks off.

Earlier today, the National Party selected Mr Bidois from a shortlist of five at a meeting in the electorate.

Mr Bidois, in his late 30s, is a former student politician, former Fulbright scholar, ex-OECD economist with a Masters in public policy from Harvard and a Foodstuffs manager.

Bidois lives in Botany, has links to influential National MPs Judith Collins and Jami-Lee Ross, and tried for the Pakuranga electorate in 2017.

He was raised and educated in Auckland, leaving school at 15 to complete a butchery apprenticeship.

"It's a true honour to be selected as National's candidate in Northcote," Bidois said in a statement.

"The hard-working people of Northcote are not a Piggy Bank for Phil Goff, Jacinda Ardern and Winston Peters to raid to pay for pet projects on the other side of the Bridge that won't benefit us here," he said.

Northcote has been a safe one for National – it won the party vote there in 2017 with 49 percent, while Labour had 34 percent.

The by-election, with a price of around $1 million, was triggered by the resignation of local MP and former health minister Jonathan Coleman.

Coleman has held the seat since he first entered Parliament in 2005 but he is moving on, taking up the role of chief executive for Acurity Health Group at the end of April.

Northcote, a traditional bellwether seat, will also be the first public test of new National leader Simon Bridges.

It is also the public's first chance to have a say on the way Prime Minister Jacinda Ardern and her Government are running the country.

If Labour manages to wrest the seat off National, it'll gain a seat in Parliament and National will lose one.

That won't change the Government's working majority much - 64 seats to 56 - as they will still have to rely on both NZ First and the Greens to pass legislation.