The two parties will outline their vision for New Zealand and their election plans this weekend at their annual meetings in Auckland.
The Conservatives have begun laying their election platform in a series of billboards and leaflet drops over the past month.
The four key planks of their campaign will be tougher penalties for criminals, a tax-free band below $20,000 of income, making referendums binding and scrapping Maori entitlements.
A few of their priorities so closely resembled New Zealand First's manifesto that leader Winston Peters said they appeared to be stolen.
"Plagiarism is what you're talking about. He's not got similar policies, he's trawled through our stuff and tried to present it as being his own."
Both parties want to end asset sales, stop the sale of farmland to foreigners, scrap the Emissions Trading Scheme and introduce tougher sentences for criminals.
Mr Craig told the Weekend Herald it was inevitable some of their policies would be similar because they were both competing for a similar pool of centrist voters. But he emphasised key points of difference.
Conservative is more radical on Maori issues, saying it will scrap the Maori parliamentary seats, repeal the foreshore and seabed legislation, and wind down the Waitangi Tribunal while not allowing any new claims.
New Zealand First says it is up to Maori to decide whether Maori seats remain.
Conservative is also more sceptical about climate change. Mr Craig has not prioritised reducing carbon emissions, while New Zealand First says it is important to switch to cleaner fuel and introduce environmental "bottom lines".
Mr Craig will use his keynote address today to speak about the need for a smaller, more efficient government with fewer MPs, agencies and advisers. This is also matched by New Zealand First policy.
Mr Craig said Mr Peters was not sincere about his smaller government policy because he also wanted to expand the powers of some government departments.
"They're talking about expanding the power of the Reserve Bank. They're talking about buying back state assets despite the fact we can't actually afford to.
"It's all additional bureaucracy."
Mr Craig said while Conservative was concerned about migrants' effect on housing pressures, he would not follow Mr Peters in using strong rhetoric against immigrants or foreign investors. He said New Zealand needed to get rid of the perception that it was unfriendly to overseas investment.
Both parties are hardline on law and order issues. New Zealand First would introduce a 40-year minimum non-parole period for murder, and a "castle doctrine" law which allowed deadly use of firearms by homeowners against burglars.
Mr Craig also wanted heavier penalties, especially for violent offences and for prison sentences to be served in full.
Law and Order
Conservative: Harsher penalties for criminals, especially in violent crimes cases. Encourage working prisons.
New Zealand First: Tougher sentences, including minimum non-parole period of 40 years for murder.
Conservative: Scrap the Emissions Trading Scheme, focus instead on localised measures such as cleaning up rivers
New Zealand First: Scrap the ETS, prioritise switch from fossil fuels to alternative fuels and introduce environmental "bottom lines"
Conservative: No sales of productive land to foreigners, encourage foreign investment in other areas.
New Zealand First: Opposes sale of farmland and forestry to foreign ownership. Only allow overseas investment which benefits NZ.
Conservative: Opposes widespread privatisation, but would not buy back partially-sold power companies
New Zealand First: Opposed to asset sales to foreign ownership and against sale of Air NZ, energy companies or partial listing of Fonterra
- Isaac Davison of the NZ Herald