United Future's Peter Dunne has lashed out at the Conservative Party, branding it "seriously extreme and nutty".

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."

Mr Craig said he was happy to meet Mr Dunne when next in Wellington.

"He should probably get to know me and ... let's have informed comment."

- © Fairfax NZ News