Cameron and Osborne at odds over marriage

The Conservative leader is pledging to reward people who get married, including gay couples in civil partnerships. But the shadow chancellor is believed to favour the State supporting parents, whether they are married or not.

Mr Cameron has recently shifted his party's focus on to more controversial-territory by urging individuals to take more responsibility for their social and economic wellbeing, as well as their health.

He has also made clear that a Conservative government would recognise marriage through the tax system and highlights research showing cohabiting couples are more likely to split up than those who have got married. Both Mr Cameron and Mr Osborne are modernisers who have changed the image of the Conservative Party and riled traditionalists.

However, differences of opinion still exist between the two men. On the issue of marriage, one Tory source told The Times: "There is a substantial disagreement. It's hard to see a way through."

One shadow Cabinet member said: "George's approach is more pragmatic, less moralising. George is cosmopolitan Notting Hill in outlook, David is more provincial Middle England." The Tories have earmarked the start of this month as "family week" and shadow children's secretary Michael Gove stressed the importance of keeping families together.

"Helping families under pressure... to commit and stay committed is one of the most effective anti-poverty, proopportunity, pro-equality steps one could take," he said. However, he raised eyebrows among some Tories in his speech to a think tank yesterday by defending single mothers and gays but only briefly mentioning marriage.