Former MP Peter Dunne says the drawn-out negotiations - or lack thereof - around forming a new Government have been "pathetic" to watch.

NZ First leader Winston Peters has vowed not to start formal negotiations until October 7, when the final results are known.

Mr Dunne, who retired from politics when polls showed he was going to lose his long-held Ōhāriu seat, says it's an "awful shambles" and a "ghastly rerun of 1996", and not how MMP is supposed to work.

"What it shows is leopards don't change their spots," he told The AM Show on Thursday.

"We're in for the same farcical procedure... It's MMP at work under his rules. It's what he tried to do in 1996, it's what hasn't happened at any election since then until now. It's certainly not MMP at work. It's just a reversion to a ghastly past."

Negotiations at the past couple of elections have been quick, because the results have been clearly in National's favour. This time they lost their partners in the Māori Party, as well as Mr Dunne.

The former United Future leader says it might not matter who Mr Peters sides with in the end, because it won't last long.

"It won't last. This guy's been fired from Cabinet once, he was fired from the coalition in 1998, he was fired by Helen Clark in 2008. Things don't suddenly get better fourth time around. This is a short-term administration we're looking at."

Especially if Mr Peters opts for the crossbenches. That means National will be left to govern alone, but rely on NZ First or another party's support for every vote - meaning the Government could fall apart at any time, forcing a new election.

"Essentially it will be on a day-to-day basis until [Mr Peters decides he's] had enough."

If Mr Dunne was running the negotiations, he'd have the Greens get over their aversion to working with National.

"Under James Shaw's leadership, I think there's an opportunity there. The yawning chasm that needs to be filled is a coherent approach to climate change.

"Sadly, the Greens seem to have too many blinkers on about doing that."

Mr Shaw would need the support of the Green Party's membership to form a Government with National however, which is seen as extremely unlikely.

"National-New Zealand First looks the most simple to do, but the number of dead rats that will need to be swallowed in the process... makes you wonder whether it's worth it, frankly," says Mr Dunne.

Newshub.