The Conservatives have been touted as a future coalition party for National since ACT leader John Banks' donations scandal. Leader Colin Craig has risen to prominence lately with controversial views on promiscuity and gay marriage.
Now Mr Dunne – who has a confidence and supply deal with National – has launched an attack on the political newcomers.
And he says he should know, as two of his former MPs – Larry Baldock and Gordon Copeland – stood for the Conservatives in last year's elections. Mr Baldock was third on the party list, while Mr Copeland stood in Hutt South.
"They're extreme," he said.
"Look at Larry Baldock's fanaticism over smacking. Copeland, the fact he left UnitedFuture over smacking, for goodness sake, when it was a conscience issue.
"Any relationship with the Conservative Party ... suggests it's going to be dogma on one side versus pragmatism on the other side, and I think it's a pretty unhealthy mix."
Mr Dunne believed the party had "little tolerance" for alternative views.
"It's a real moral jihad; it would be smacking, not just resisting any change to the abortion laws, it's tightening the abortion law, it's anti-prostitution, you name it, the whole suite of agenda items.
Ooh, ooh, you care about something... Extremist! And you're prepared to do something about it... Extremist! Oh, oh, and you think these things matter and they'll have long term ramifications ... Extremist! Extremist! Extremist!
So, why does smacking matter? Because it's too much of an intrusion into the family by the Government that subverts parental authority and therefore proper guidance, over children. This issue galvanised New Zealanders enough to get them out signing a petition for a referendum and then voting in that referendum en masse, the result of which the Government ignored. The State is a terrible parent and wrestling power from families in this way is a precedent for more intervention as time goes on. Not to mention the families that have been persecuted to date by the law in New Zealand. But obviously concepts and realities of that nature just go over Dunne's head.
Related links: Dunne attacks 'moral jihad' extremists ~ Stuff
Some of our posts on the anti-smacking law
The anti-smacking law, why parents are criminals
Smacking law referendum not being held with General Election
What is wrong with John Key?