Election 2020 battlegrounds: North Island electorates to watch - Whanganui, Ōhāriu, Wairarapa, Palmerston North, Hutt South, Wellington Central

Labour MP and Hutt South candidate Ginny Anderson will again go up against incumbent Chris Bishop. Photo / supplied

The country's most marginal seat and retirements opening up the contest in other seats - the North Island has a number of intriguing electorate battles this election.

Whanganui

Labour fancies an upset over the incumbent, National MP Harete Hipango, who took over from Chester Borrows after winning 1706 more votes than Labour's Steph Lewis in 2017.

Lewis, a 32-year-old trained lawyer who has worked for the Privacy Commission, is back for another tilt at capturing what has now been a National seat for five terms.

National Party and Whanganui MP Harete Hipango. Photo / Stuart Munro

Standing in her way is Hipango, who before politics worked as a lawyer for more than 25 years and was a member of the district health board.

She is National's spokesperson for Crown-Māori relations and Māori tourism, and the shadow Attorney General, and recently hit the headlines for a Facebook post attacking Jacinda Ardern over "rank and atrocious" abortion law reforms.

WHANGANUI

The Green Party is standing Alan Clay, a writer, teacher, clown and film director, and who will focus on the party vote and has endorsed Lewis for the seat.

Ōhāriu

NZ First MP and minister Tracey Martin. Photo / Mark Mitchell

Former police union boss and Ōhāriu MP Greg O'Connor says it's "all or nothing" as he bids to defend one of the country's most marginal seats - which has a surprise new contender.

O'Connor has taken himself off the Labour Party list, meaning if he falls to National MP Brett Hudson he'll be out of Parliament.

He won the wealthy Wellington electorate by just 1051 votes in 2017, after 33-year representative and United Future Peter Dunne quit the campaign only two weeks before the election and as Jacinda Ardern turned around her party's fortunes.

OHARIU

Hudson is a former IT professional who has been a list MP since 2014 and is currently the party's spokesperson for police and government digital services. He's looking forward to a full campaign - last election National had told voters to back Dunne until he pulled out.

An already fascinating contest has been further shaken up by NZ First standing its MP Tracey Martin, who has been in Parliament since 2011 and is Minister for Children, Internal Affairs, Seniors and Associate Education Minister to boot. Martin has previously stood in the Auckland seat of Rodney, but has moved to Ngaio and will try to boost NZ First's party vote as it scraps for survival.

Wairarapa

Labour MPs Greg O'Connor, left, and Kieran McAnulty are each standing in electorates to watch this election. Photo / Christine McKay

An electorate that will have a new MP after the incumbent, National's Alastair Scott, retired after two terms.

Farmer Mike Butterick has been chosen as the National candidate and will look to defend Scott's 2872 majority in the previous election, held over Labour list MP Kieran McAnulty, who is back for his second election after becoming the party's junior whip.

WAIRARAPA

NZ First list MP and Defence Minister Ron Mark will be campaigning again in his trademark cowboy hat, having captured nearly 20 per cent of the vote last election, and the Greens have put up former Wellington Mayor Celia Wade-Brown.

The seat encompasses Masterton, Carterton, Featherston, Greytown and Martinborough. About 86 per cent of residents are NZ European, and nearly half are aged over 45.

Palmerston North

William Wood, National candidate for Palmerston North. Photo / supplied

Iain Lees-Galloway quitting politics after an affair with a staffer means Palmerston North voters face a choice between a deputy mayor and a National candidate barely out of school.

Labour has selected Palmerston North Deputy Mayor and former secondary school teacher Tangi Utikere, who is the frontrunner over National candidate and 18-year-old William Wood.

PALMERSTON

Lees-Galloway had held the seat since 2008 and won by roughly 6000 votes in 2017, although the party vote margin is slimmer.

Wood became one of the youngest electoral candidates ever when selected by National last year and aged just 17. The teenager and youth diplomat defeated National MP Jo Hayes to secure the nomination.

NZ First MP Darroch Ball is also standing and seeking the party vote, as is Green candidate and climate campaigner Teanau Tuiono, who is ranked eighth on his party's list and in with a chance of becoming an MP.

Hutt South

One of the tightest races will likely be in Hutt South. In 2017, National MP Chris Bishop took the seat from Labour for the first time, winning by just 1530 votes.

Labour stalwart Trevor Mallard held the seat since it was created in 1996, but Bishop came within 709 votes in 2014, and Mallard subsequently went on the list and became Speaker of the House.

HUTTSOUTH

His replacement Ginny Anderson, a policy manager at NZ Police, entered Parliament as a list MP in 2017 and will again go up against Bishop, who at 36 is the shadow leader of the house and National's transport and infrastructure spokesperson.

Other candidates include former NZ First MP and Corrections officer Mahesh Bindra.

Wellington Central

National Party list MP Nicola Willis is running in Wellington Central. Photo / Mark Tantrum

There's little chance of Labour MP and Finance Minister Grant Robertson losing, but Wellington Central will still get plenty of attention thanks to the profile of contestants.

Robertson got nearly 50 per cent of the vote last election, and his opponents - including up-and-coming National MP Nicola Willis and Green Party co-leader James Shaw - will be trying to boost the party vote.

WELLINGTON

Willis, a first-term list MP, has been promoted to National's spokesperson for education and early childhood after Nikki Kaye resigned. Shaw has said he wants to boost the Green party vote back up to about 30 per cent, from 21 per cent last election.

If Wellington Central was representative of the country, then The Opportunities Party (TOP) would have cleared the 5 per cent threshold in 2017. Abe Gray, who founded a cannabis museum, will be hoping for a similar result as voters also mull the referendum on legalising cannabis.