NZ Election 2020: Judith Collins vows National will do 'whatever we have to' to get power back; thinks NZ First, Greens won't get into Parliament

National is open to working with a variety of parties to wrestle power off Labour, Judith Collins says - but she doesn't think the Greens nor New Zealand First will get enough support to make it to the negotiating table.

The new National leader, who took over from predecessor Todd Muller on July 14, says she doesn't believe either party will make the 5 percent threshold required to get into Parliament.

In the most recent Newshub-Reid Research poll, the Greens were sitting at 5.7 percent, ominously close to dropping beneath the threshold, while New Zealand First had plunged to a disastrous 2 percent.

The poll also had National on a dreadful 25.1 percent, compared to Labour's 60.9 percent - but Collins has remained optimistic she can turn things around before the election on September 19.

Speaking to Newstalk ZB on Monday morning, Collins wouldn't rule out working with anyone to form a coalition, but said long-time ally ACT would be the National Party's first choice.

"I always maintain that we should see how things work in the election, because obviously we have to do whatever we have to do to take back the country into a path of economic development," she told morning host Kerre McIvor.

"We need to do that, but we also have a very good and close relationship with the ACT Party - I'm not going to make any bones about it.

"I get on very well with [ACT leader] David Seymour, I think he's a person of principle - and frankly I'd rather deal with people of principle than people that don't have any principles."

Collins refused to name anyone in Parliament she deemed not to have principles - presumably so she doesn't burn bridges with potential coalition partners - but said National had proven it can work with parties with very different ideologies to their own in the past.

However of the two parties Collins name-checked, New Zealand First and the Greens, she believes both will bomb at the election - and thinks that will allow National to seize power.

"I've dealt with people in New Zealand First, but I don't think they'll be back this election… I think a lot of people have lost any confidence in them, so I don't think they'll be back," she said.

"Even if you do put polls together and make much of them, if you put National and ACT together, New Zealand First goes and Greens go - which I think they probably will, too - and you end up with a National-led Government with ACT."

It's unclear how Collins believes she will wrestle power from Labour and Jacinda Ardern, who are polling so well they could govern alone as it stands.