New Zealand First leader Winston Peters says he is staggered by the National Party's tax policy.
Under National's policy it would scrap the research and development tax credit and make changes to KiwiSaver to help pay for its tax cuts.
At a Grey Power meeting near Paraparaumu on Thursday, Mr Peters described the policy as disgraceful in the extreme.
"Here's a conservative party which worldwide has as the main principle of its thesis as an economic and political philosophy savings, arguing that we should jettison KiwiSavings in this country," he said. "I couldn't believe what I heard but it's so typical of the modern National Party - no economic theory or principle whatsoever."
Mr Peters says New Zealand First proposes lowering GST to 10%.
ACT Party leader Rodney Hide has also criticised National's overall economic plan, saying it simply continues Labour's big spend-up.
The Labour Party has criticised proposed changes to KiwiSaver and some businesses disagree with National's plan to scrap the tax credit for R&D.
National Party leader John Key has dismissed concerns about doing away with the tax credit and says his party's policy will be good for economic growth, helping consumers and businesses.
Mr Key says investing in high speed broadband and simplifying the Resource Management Act will help businesses.
Grey Power heckler
A Grey Power member was nearly thrown out of Thursday's meeting with Winston Peters for persistently challenging his views.
