The Prime Minister has rejected suggestions the National Party's mandate has been weakened after it lost a seat following the counting of special votes.
National had 60 seats on election night but in the official results declared by the Electoral Commission on Saturday afternoon, which include special votes, it has 59 seats.
The Green Party has picked up the seat from National and now has 14 MPs.
Greens co-leader Russel Norman says the change means the government is now very, very marginal and National needs to think through whether it has a mandate to force through privatisation and other unpopular policies.
But the Prime Minister, John Key, says the loss of a seat makes no difference to National's ability to govern for a second term, given the support of ACT and United Future.
He says he has formally advised the Governor General of his intention to form that Government and expects to name his Cabinet on Monday.
Mr Key says he is also very optimistic that National will sign a deal with the Maori Party as early as Sunday afternoon and that will extend the majority to 64 out of the 121 seats in Parliament.
He says that, even with 61 seats, his government would have a "very rock solid majority" since there are "less moving parts" with only one member of the ACT party and one from United,
"I'm very confident we not only have a mandate but the capability to change to SOE legislation that will allow those partial sales to take place."
The extra seat to the Greens means Mojo Mathers, who is number 14 on the Green Party list, will enter parliament.
As the country's first profoundly deaf MP, Ms Mathers says she'll be fighting hard for the rights of disabled people.
She will be the Green Party's spokesperson on disability issues.
Referendum vote for retaining MMP
In the referendum on the electoral system people voted overwhelmingly in favour of retaining the current system.
MMP received 57.77% support, while 42.23% voted to change the electoral system.
Most of those votes for change wanted New Zealand to go back to first-past-the-post.
The pro-MMP campaign has welcomed the vote, saying the final result is above the 54% support predicted in the polls.
Spokesperson for Keep MMP Sandra Grey says no system is perfect but now is the time to fine-tune MMP, which she says is likely to remain New Zealand's electoral system for at least 50 years.
