Tune into Newshub Live on Three at 6pm Thursday night for the final Newshub-Reid Research poll before election day.

National is "digging in" on its claims about Labour's so-called fiscal hole - Paula Bennett's own words - despite accusations of lying and "post-truth" politics.

The Deputy Prime Minister and Labour's fifth-ranked MP Phil Twyford went head-to-head in a fiery encounter on The AM Show on Thursday morning, two days before voting closes in the tightest election campaign since 2005.

The latest polls have National and the Labour-Green bloc neck-and-neck - Labour's support slipping as National unleashed a series of attack ads about the party's tax plans.

"These guys have got nothing left in the tank after nine years except lying - flat-out lying - and trying to frighten people into voting for them," Mr Twyford told host Duncan Garner. "We've run a relentlessly positive campaign."



"Except for calling people liars, but that's okay," Ms Bennett hit back, suggesting Labour is losing the "contest of ideas" and it's a losing strategy.

"What [voters] do think is you sit there and resort to name-calling and calling people liars and things when you're not quite getting your way. That's fine Phil, but that's actually what people think."

National's ads claim Labour is going to raise taxes on the average earner by $1000 a year. The logic is National has passed a law to cut taxes for people earning $52,000 or more by $1000 a year (it's less for earners below that annual wage), and to pay for its promises, Labour will have to reverse that legislation.

"This is not a whim, this is not a thought, this is not something we thought up a couple of weeks ago," said Ms Bennett. "Labour will have to change the law so the average wage earner does not get $1000 more in April next year... it's locked, it's loaded, it's in law."

Coming so soon after controversial claims there's an $11.7 billion hole in Labour's budgeting, Mr Twyford said National's "whole campaign has been based on lies" and lamented the fact that based on the latest polling, it seems to be working.

"I'm not surprised that some people might have got a bit confused by the Finance Minister and the Prime Minister going on TV and lying like flat fish... What are the kids going to think with the Prime Minister and the Finance Minister lying like flat fish in the media and running a campaign of scaremongering?"

Forced to say one nice thing about the other party's policy platform, Mr Twyford said he has "respect" for the work Chris Finlayson has been doing with Treaty settlements, while Ms Bennett cited Labour's support for initiatives around homelessness.

Newshub.