National leader Christopher Luxon has pushed back on criticism over his party's record on paid parental leave, saying he is focused on the future.

National on Sunday announced extending paid leave to 30 weeks and allowing parents to take their leave at the same time.

Speaking to RNZ Morning Report  programme on Monday, Luxon said National had strong values of supporting families.

"There's just no better way to 'build the future' than building stronger families, and supporting future mums and dads in the work that they do ... is just so important ... but it's also an expensive time."

Labour criticised the party over the policy, pointing to National having blocked an extension to paid parental leave in 2016, and saying cuts to Best Start payments, reduced funding for school lunches, and restarting pay equity negotiations had made things harder for young families.

Luxon said he was focused on the future.

"I'm sorry, I only came to politics in 2020 ... I don't know what happened in the past, I'm focused on the future and this is a really important policy for me and for our future and for our party and we think it's a really good thing for working mums and dads around the country."

The ACT Party had questioned the timing of National's announcement, which came following Stuart Nash’s resignation as a New Zealand First candidate after suggesting Katie Nimon, National's MP for Napier - which Nash was looking to contest - was "the laziest" for the amount of leave she took after having a baby.

Luxon said he could not have predicted Nash's comments.

Polling points to risk of list losses

Luxon made the comments as National was also at risk of losing some of its top performers.

The party got 28.7% in this month's RNZ-Reid Research poll, which would give National 36 seats in the House, down from its current 48 - or 49 if you count the vacancy recently left by Judith Collins.

The party’s strong performance in the electorates in 2023 means it has just five list MPs: Nicola Willis, Paul Goldsmith, Gerry Brownlee, Melissa Lee and Nancy Lu.

Willis, who is running as a list-only candidate, was not concerned that she may not get back into Parliament.

"No, I'm not concerned at all, because National has a vision for the future. We are fixing the basics, we are building the future, and the policies that we will set out to the New Zealand public will see our polling increase.”

Similarly, Lu was confident, saying "absolutely" when asked whether National would get enough of the party vote to see her return.

Goldsmith, who contests the Epsom seat held by ACT leader David Seymour, was not sure whether he would be back in Parliament on 28.7%.

"It depends on a whole lot of factors. But I'm sure we're going to do a lot better than that."

Hutt South MP Chris Bishop has said it would be "highly unlikely" he would retain his electorate seat on current polling.

Victoria University associate professor of politics Lara Greaves said there was not much else National could do to protect its stalwarts, other than boost its party vote.

She believed National would hold most of its electorates, which has its own problems.

"That creates a bit of an issue for National long-term and a structural issue in the way that their party is run, because if they're going to hold these electorate seats, they're not going to be able to bring in very many people from the list over time, and that's going to mean that it's just going to be all the more important for their kind of stars, their kind of more experienced MPs, to have these safe seats."

With the Opportunity Party banging at the door of 5%, there was a risk that even fewer list spots became available.

"That 5 percent that Opportunity gets has to come out of everyone else's party vote, or the percentage of the House they're entitled to through list seats and their electorate seat makeup. So it does impact the larger parties more in terms of their allocation of seats," Greaves said.

Labour leader Chris Hipkins said it was a problem all of National's own making.

"National's facing this conundrum because they've completely failed to deliver on the promises they made New Zealanders."

The general election is on November 7.