Strange things happen in by-elections

When historians search for clues to the ousting of one of our most popular governments, they will probably trace it to the Northland by-election.

Few by-elections have gone so spectacularly off the rails as Northland, which was won by NZ First leader Winston Peters after former prime minister John Key gave him ‘‘zero chance’’.

It set up a grudge match two years later when National threw everything at wresting back Northland in 2017 as part of a campaign to wipe out NZ First. It failed, and Peters’ rejection of a coalition with National was to teach them a lesson.

But by-elections are feared precisely because of unexpected turns that make laughing stocks of politicians and pundits.

Which is why the Northcote by-election might look like a romp in the park for National – but could be anyone’s. National launched its campaign on Sunday, and has a lot riding on its candidate Dan Bidois holding the seat.

National’s leader Simon Bridges knows better than most how quickly things can turn ugly. He was at the sharp end of the Northland drubbing, scarpering up there early to promise locals 10 new bridges. That backfired spectacularly and came to symbolise National’s neglect of provincial New Zealand. But National mishandled just about every other aspect of its Northland campaign as well. It took too long to select its candidate, Mark Osborne, and gave Peters a flying start.

It was blindsided by Labour’s tactical endorsement of Peters, and under-estimated the depth of anger over local issues like roading and infrastructure. It also took for granted that Northland was a safe blue-ribbon seat. But voters often see by-elections as a chance to lodge a protest vote without risking a change of Government.

Low turnout is also a factor in most byelections.

So could National lose Northcote? While outgoing MP Jonathan Coleman won the seat with a 6000-plus majority, Northcote has previously been held by Labour and is known as a ‘‘bellwether’’ seat, meaning the vote mirrors the country as a whole. That seems to be the case in 2017 as well, when the party vote percentages broke down roughly in line with the National vote.

Some polls suggest Labour’s support has increased since election night, which could have an impact – and National’s new candidate will be contending with a lack of name recognition compared with his predecessor.

Being in Opposition could also affect National’s share of the vote – though National has been gifted a good local issue to run hard on, regional fuel taxes.

With millions of dollars left in the coffers after the election, National has plenty of money to throw at an advertising campaign on traditional and social media, attacking the government over the impact of those taxes on Aucklanders.

National’s regional road show has been supported by a strong billboard game, also thanks to the healthy state of its books. But National has the most to lose from a defeat in Northcote. Bridges is still largely unknown to most punters and needs a win to enhance his credentials.

Labour, on the other hand, will talk up its status as the underdog but can’t afford a heavy defeat, particularly if the by-election turns into a referendum on the May budget.

Victory would mean more than an extra seat, however. It would be a huge morale boost, handing Labour back the political agenda while National licked its wounds.