National Party leader Christopher Luxon says another hike in interest rates would bring pain and suffering for New Zealanders.
The Reserve Bank is expected to raise the official cash rate again today by another 25 basis points to 5 percent, a level last seen in December 2008.
Luxon told Morning Report 19,000 families were already in mortgage arrears and the government's mismanagement of inflation was driving the problem.
"We're seeing a huge pain and suffering going on across New Zealand and it's going to get worse."
Many people would need to refix their mortgages in the next six months, he said, "and that's going to be incredibly tough and difficult".
Interest rates were rising because inflation had gone up, Luxon said.
"The economy's now shrinking, [there's a] risk of recession and risk of rising unemployment - that's the pattern of economic history and because the government hasn't managed inflation well, we're dealing with higher interest rates."
'People should love who they want to love'
Luxon defended his party's vetting process for candidates in the wake of revelations about its Maungakieie candidate Greg Fleming's past comments on civil unions.
Fleming criticised civil unions in 2004, and questioned why the government did not also recognise incestual or polygamous relationships.
On Tuesday he distanced himself from those comments.
Luxon said party officials and delegates were aware of Fleming's past comments on civil unions - but they were not raised with him.
He denied he had been blindsided by the revelations this week.
"The party vetted [Fleming], was aware of those issues, they discussed them with him. He talked about them freely," Luxon said.
"Greg made his comments 20 years ago and he clarified them very quickly yesterday, which was very good.
"I want to be crystal clear - they are not positions or remarks that I hold; I'm a big fan of same sex marriage, people should love who they want to love, so that's really clear for me."
Luxon said National had put "really good processes in place" around candidate selection.
"I think that it's really good that people are actually open, they're upfront declaring the issues from their past," he said.
"If you have to have a perfect past in order to come to this place, there won't be many people in it."
Ardern 'represented the country incredibly well'
Luxon said former prime minister Jacinda Ardern, who will give her valedictory speech in Parliament tonight, had shown "exemplary leadership" following the Christchurch massacre.
"I think she made all New Zealanders proud," he said.
"I thought she carried herself and represented the country incredibly well."
Luxon said he believed Ardern had good intentions as prime minister, but did not deliver.
"When you look at what's happening with our economy, health, law and order, education, crime ... all those outcomes have gone backwards."
However, she had "obviously kept our profile internationally in a good place, which is important".
"I wish her nothing but success and wish her and her family incredibly good things for the future."