The scant evidence we have on the coalition negotiations suggests Winston Peters is "absolutely smashing" National and Labour, according to Newshub political editor Patrick Gower.
Neither side has revealed what's been talked about in the week-long talks, except to say they've been focused on policy.
"It's just been about policy and nothing else," Labour deputy Kelvin Davis told The AM Show on Friday.
"We've just discussed policy," added National deputy Paula Bennett. "It hasn't been the talks about the jobs and things."
Gower says this proves they're both "hostages" to Mr Peters, who is in "total control".
"They haven't got to kind of formation that a Government will have," he told AM Show host Duncan Garner.
"That means Peters is totally owning both sides. What he's gone and done is banked his policy gains. I expect him to get over 30 - mark me down as saying that. But what he hasn't said to them is 'this is the kind of Government that we will have'.
"He could now go back to National and say, 'Thank you for the policy gains. I wouldn't mind going with you, but I will sit outside your minority Government... you will need to get my vote on every single issue and I will make your life a massive pain, and I will put myself at the centre of things.' And National will have no negotiating power over the policies he's banked.
"Conversely, he can go to Labour and say... 'I want to shut the Greens right out.'"
Both Labour and National will give Mr Peters what he wants to get NZ First in a formal coalition, Gower says, because the alternative is to "cap-in-hand" to him "for everything".
"It would make him more powerful than some Cabinet ministers... He could be at the centre of politics for the next three years."
Mr Peters was expected to announce his decision on Thursday, but extended the deadline so NZ First board members could meet to discuss what each of the parties has offered.