Green Party co-leader James Shaw says replacing Winston Peters as Deputy Prime Minister is "not out of the realm of possibility", based on the latest polls.
Two polls this week had good news for the left, both suggesting a Labour-led Government would be formed after October's election.
While one had Labour able to govern alone, the other said they'd need a support partner - and with the Greens, the only other left-wing party looking likely to make it back into Parliament, Shaw is flexing.
At the weekend he said a vote for the Greens would help keep Prime Minister Jacinda Ardern in the top job, on Tuesday adding it might nab him the deputy role.
"That role, like all of the other ministerial positions, is something that we'll discuss after the election," he told RNZ's Morning Report.
"It depends on the numbers, it depends on the shape of the agreement that we've got, it depends on the extent to which we think it can help us to advance the programme of work that we have. It's not out of the realm of possibility."
New Zealand First is on just 1 percent in the polls, and looking likely to be knocked out of Parliament for the second time in its history. It currently has a formal coalition with Labour, while the Greens have a confidence and supply agreement.
Shaw said whether he'll push for the deputy role depends on whether the party feels it will advance their goals, acknowledging it comes with "constraints" too.
Former Prime Minister Helen Clark, who led Labour for 15 years, said Labour and Ardern should "seriously consider" signing a coalition agreement with the Greens even if they have enough MPs to govern alone.
"Politics is about long-term relationships and not burning bridges. She'll want to see where the numbers lie, but for what it's worth I think there's been some very good leadership on key issues by James Shaw, and I think it's actually been a good working relationship," she told The AM Show.
During her three terms as Prime Minister, Clark didn't form formal coalitions with the Greens, but did sometimes rely on them for confidence and supply. Since the first MMP election in 1996, no party has ever won an outright majority.
"No one ever has under MMP, but there's a first time for everything," said Clark. "The last election was the first time the largest party didn't end up leading the Government. MMP is very adaptable - let's see. It's feeling a bit like the 2002 election."
In 2002 Labour romped home to victory, with National falling to its worst-ever defeat. Like now, Labour was polling in the 50s in the lead-up to the election - but fell to 41 percent on the day.