National MP Katherine Rich is likely to be the last MP standing in her caucus of 48 who supports Sue Bradford's anti-smacking bill when it finally passes.
"It is not what I expected," she said last night. "But I am privileged to be in a party that allows me to express those views."
She said National had always had a "small pocket" of social liberals.
"When Ralph Hannan [Justice Minister in the Holyoake Government] started talking about the equal distribution of matrimonial property and getting rid of capital punishment, people thought he was a nut. But slowly over time the community changes."
The National caucus has allowed a free vote on the Bradford bill, which bans the use of physical punishment on children.
West Auckland list MP Paula Bennett was thought to be another supporting the private member's bill but she said she had not made up her mind and had sent out 19,000 letters to voters seeking their views in a telephone poll.
By yesterday she had received only 200 replies and 66 per cent wanted her to oppose the bill, so on the basis of that she probably would.
"I am honestly and genuinely conflicted," Ms Bennett said.
National Party leader John Key said he was quite relaxed about Mrs Rich's position.
Mr Key said he had not given up attempting to gain support for an amendment that would state that minor and inconsequential smacks by parents would not be covered by the bill.
But Ms Bradford, a Green MP, confirmed yesterday that she would withdraw the bill if that happened anyway.
Mr Key plans to contact Maori Party co-leader Tariana Turia over the weekend and New Zealand First MPs next week.
Meanwhile, the Anglican Church is organising an ecumenical service for peace in families at the Wellington Cathedral on Wednesday at 1pm.
At the same time, across the road at Parliament, Destiny Church will hold a protest rally to mark the return of the bill to the debating chamber.
The Anglican Church's social justice commissioner, Anthony Dancer, said last night that the rally would involve Anglicans, Catholics, Methodists, Presbyterians and other mainstream church members on an individual basis.