Paula Bennett has angrily hit back at claims the party is lying about Labour's proposed budget, saying the party's not supposed to be "doing nasty politics".
National finance spokesperson Steven Joyce earlier this week said Labour made an $11.7 billion mistake in its alternative budget - a claim which has been widely debunked by economists.
Labour leader Jacinda Ardern called it a "lie" during Thursday night's Stuff Leaders' Debate, and her deputy Kelvin Davis kept the attacks coming during an appearance alongside Ms Bennett on The AM Show on Friday morning.
"Steven Joyce told a big fat lie, it backfired, he was found out," Mr Davis said.
"There's seven stages of lying - there's tell a lie, repeat a lie, justify the lie, perpetuate the lie, then deny, deny, deny. So Paula, what stage of the lying process are you at?"
"Oh well," replied the Deputy Prime Minister. "I think everyone agrees there's a big hole in your numbers."
"Perpetuating the lie," said Mr Davis, staring at his rival.
"Don't sit next to me Kelvin and call me a liar, because that's not on, buddy," replied Ms Bennett. "You're not supposed to be doing nasty politics."
Asked if she trusted Mr Joyce to have got his calculations right, Ms Bennett said she did.
"That's the numbers that they got when they did the accounting. I haven't gone through it line by line, but I do, if that's what they say it is."
Mr Davis couldn't believe what he was hearing.
"You cannot sit there and say that... There is no economist that has said there is a hole in our accounts and they're just perpetuating the lie."
What the economists have said is that Labour is running a very fine line. Mr Davis says as the figures are based on the Treasury-supplied Pre-election Economic and Fiscal Update, the same goes for National.
"They're trying to deflect to us when in fact, they have a problem as well," he said. "In the last three weeks these guys have made $12 billion in promises - $10 billion in roads - and we're still waiting for 10 bridges up north that haven't eventuated."
Ms Bennett said as a capital expense, the roads have in fact already been budgeted for.