Winston Peters and his New Zealand First Party would decide the next Government if an election were held tomorrow.
The latest 3 News/Reid Research poll shows the veteran MP is needed to get both Labour and National into power.
Mr Peters open admits it will be his party that decides the next Government.
"I'm the only leader that can say, 'Whatever the outcome is, to our voters, you will get to decide the next election.'"
Unsurprisingly, he's refusing to say which side he's leaning toward.
"I'm saying to all those hundreds of thousands of people who vote New Zealand First: the great thing about your choice is you'll get to decide the next election. No other leader can say that."
But Mr Peters has dropped as preferred Prime Minister, down nearly 3 percent to third place.
The results have riled ACT Party leader David Seymour.
"He's got enormous talents as a politician, but he is abysmal as a policymaker," says Mr Seymour. "It's public policy that really matters to New Zealanders."
Meanwhile Mr Seymour is upbeat, despite getting just 0.6 percent in the latest 3 News/Reid Research poll.
He says the party is taking small steps and plans on having four MPs in Parliament in 2017.
"We've got a rebuilding job to do," he says. "We always knew that. Nothing's worth doing if it isn't hard."
The poll has National on 47 percent, Labour on 33 percent and the Greens on 10 percent.