Simon Bridges has taken the biggest punt of his career - and his attempt to kneecap New Zealand First by refusing to work with them could easily turn him into a political cripple.

It either shows a lack of understanding of MMP, or he's a high-risk betting man.

Bridges insists it was his call to refuse to work with Winston Peters and claims his party is, to a person, happy and relieved by his decision not to work with NZ First "in any way, shape or form".

The National leader has jumped the gun, declaring his hand way too soon.

His decision is quite different to the same decision made by John Key before the 2008 election. Key had options; namely the Maori Party, United Future and Act.

That move saw NZ First out of Parliament, mainly because of a donations saga it had become embroiled in, and even though Key rejected them again in 2014, they were back with a vengeance with eight MPs.

Currently, Bridges has just one option, with just one MP, thanks to an ongoing soft deal with Act in the Epsom seat.

And that's what MMP is all about, whether we like it or not: It's cutting deals.

It's as though Bridges has rejected MMP, believing National will be first past the post with 51 percent of the vote at the coming election, something no party has achieved since the electoral system came into being in 1996.

So Labour has now been given plenty of time sharpen it's electoral pencil, doing the sums in Northland, a seat Peters lost at the last election.

• 'I don't trust NZ First': Bridges rules out post-election deal with Peters

The sums will tell them he, or possibly Shane Jones, could pull it off if they do an Epsom deal there, sacrificing the electorate vote in a seat they're unlikely to win anyway.

It also gives New Zealand First time to strategise about how they pitch themselves to the electorate; no longer the kingmaker, but the handbrake on the crazies.

National failed before the last election to wipe New Zealand First from the political map, even though Bill English pleaded with voters to cut out the middle man.

And that's what this is all about with Bridges. He's telling voters if they want a National Government they'll have to vote for it.

He insists Peters can't be trusted but, when asked why, came up with a curious argument which cuts to the heart of what MMP's all about, again whether we like it or not, saying the public is sick of the charade of Peters holding the country to ransom for weeks while he makes up his mind on who to anoint as Prime Minister.

Bridges may have removed the choice from Peters, but he's just increased the odds against him getting the job he so desperately wants.