New Zealand First leader Winston Peters insists the party is not facing three years of irrelevancy, and can achieve reform through select committees and by keeping the Government under intense scrutiny.
On Saturday, Mr Peters led the party to a remarkable comeback after three years out of Parliament, and its 6.8 per cent of the party vote will put eight MPs in the House - the party's best result since 2002.
The party will sit on the Opposition benches and vote issue by issue.
Yesterday, Mr Peters all but ruled out a Memorandum of Understanding with National, a deal the Green Party has had and is expected to have again for the next parliamentary term.
"The Greens can run with the hares and hunt with the hounds as they've done, but that is not going to impress a lot of their supporters as time goes by," Mr Peters told the Herald.
But the hostility Prime Minister John Key has shown towards Mr Peters has raised questions about what New Zealand First can achieve.
Asked about the prospect of Mr Key simply ignoring him for three years, Mr Peters said: "He wasn't ignoring me by the end of this campaign, and he sure had the smile wiped off his face."
Mr Peters said his party's votes while in Opposition had been needed to help create the Cullen Fund, KiwiSaver and Kiwibank.
"Those who make comments about opposition not having any value don't understand the power of Parliament and how it can be used. I'll tell you what you do to push reforms: You turn up the heat on those in Parliament who want to protect their mates."
Select committees, including finance and expenditure and foreign affairs and trade, would be an important tool for New Zealand First.
"If you turn the heat up on something that's palpably wrong, you can change legislation," Mr Peters said.
He said the party would support Government policy where it aligned with what New Zealand First believed in, such as increasing research and development spending.
He also supported in principle National's proposal for civil detention centres - indefinite detention for the worst offenders until the Parole Board deemed them safe to be released.
"I'll have to see the detail, but letting people out who are a clear and present danger to the community is madness, even if they've served their time."
But he is staunchly opposed to partial asset sales, the Emissions Trading Scheme and welfare reform in the absence of jobs.
Former North Shore mayor Andrew Williams, the party's number three, said he had not considered the deputy leadership, but he "wouldn't mind either way".