National's win in the Northcote byelection guarantees that the party will be fizzing when the House resumes tomorrow after the recess.

It has already been licking its chops at the prospect of making Jacinda Ardern squirm over ministers Kelvin Davis and Shane Jones.

She can also expect the Bunsen burner to be turned on to herself and Megan Woods over oil and gas, although whether she stays in Wellington after today's Cabinet is not certain with her due date next Sunday.

Davis accused National's Jacqui Dean of being "hysterical" when she put him under pressure over tourism issues at a select committee (and has since apologised).

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Jones gloated about his home base of Northland getting much of New Zealand First's so-called $1 billion slush fund (no apology necessary when truth is his defence).

And official documents confirmed the Government was warned that ending new offshore oil and gas exploration was likely to increase carbon emissions not lower them before Ardern and Woods announced a momentous decision with the inverse level of inquiry.

On top of those issues, the byelection win by Dan Bidois with a slimmed-down majority of 1362 has been a huge boost for National.

It wasn't just that National held on to the seat but it was how it kept the seat.

Despite the turnout being down from 77.57 per cent of registered voters in September to an estimated 43.7 per cent in the byelection, support for the National candidate remained about the same percentage of votes cast.

Former National MP Jonathan Coleman, with a majority of 6210, won 52.77 per cent of the vote in 2017 (higher than the party vote) compared with a barely changed 51.1 per cent for Bidois.

Speculation over what that means for the next election remains just that because the party vote will be in play, unlike in the byelection.

The Greens weighed in behind Labour's Shanan Halbert on Saturday to lift Labour's percentage of the vote from 35.59 per cent to 44.2 per cent.

That enabled Ardern to claim some success from the campaign and congratulate the hundreds of Labour volunteers.

Assuming Halbert stands in 2020, as a third-time candidate with a good campaign record, he can expect a much improved list place than the No 51 he got in 2017 - nine list candidates are ahead of him on that list.

Bidois will have the benefit of incumbency.

But he will have nothing like the ground support organised in the byelection by deputy leader Paula Bennett.

Labour has traditionally been better known for its strong ground game - but National is trying to match it.

On Saturday National knocked on 5000 doors in the electorate to remind people, the ones it believed would vote National, to vote.

Bidois will certainly be the toast of the National caucus tomorrow but he should savour it. After that, he will be on his own.

NORTHCOTE CANDIDATE VOTE (total votes and party's percentage of votes cast)
2018 BYELECTION (preliminary)
National 10,147 (51.1%)
Labour 8785 (44.2%)
Greens 579 (2.9%)
Majority 1362
Turnout of registered voters estimate 43.7 per cent

2017 GENERAL ELECTION (official)
National 19,072 (52.77%)
Labour 12,862 (35.59%)
Greens 2457 (6.8 %)
Majority 6210
Turnout of registered voters 77.57 per cent