The Green Party says the Prime Minister plans to jack-up the election with deals for electorate seats for potential support partners.
John Key has already said who National could work with after the election, but won't reveal details of any electoral arrangements until the weeks before polling day.
Green Party co-leader Russel Norman claims Mr Key is concocting dirty deals all over the country.
Mr Key says whether he does any deals at all will depend on different factors, including how parties are polling in the run-up to the election.
He also won't say when the election may be held. He says the G20 meeting in Australia in the middle of November is a complicating factor and will only say the election can be expected in the second half of this year.