Conservative Party plans to offer tax breaks to married couples have been criticised by opposition parties as bribes amounting to “social engineering”.
David Cameron is under pressure to explain what type of financial incentives would be offered to married couples under his government, after admitting that transferable tax allowances were unaffordable.
Both Labour and the Liberal Democrat Party say the policy is in disarray.
In an interview with The Sunday Telegraph, schools secretary Ed Balls said "marriage is the most important institution for making sure we have strong and stable families".
However, he added: “The idea of trying to socially engineer family life through a tax policy… is hugely expensive and unfair."
Appearing on BBC One's Politics Show, Balls explained his party's view that supporting all strong relationships was the best way to help children.
Meanwhile, Nick Clegg, leader of the Liberal Democrat Party, slammed tax breaks for married couples as immensely unfair - and warned they would disadvantage and sitgmatise many families.
He also queried how the Tories could ask taxpayers to pay billions of pounds towards a “tax bribe for people who simply hold up a marriage certificate”.
But Cameron insists that rewarding couples who marry will be a cornerstone of his party’s policy.
“I don’t believe governments can make families work or stick together,” he says. “But I do believe the state can support families as they deal with all the different pressures that they face.”
Writing in the Mail on Sunday, Cameron also argued that children need a stable home: “That's why we'll back commitment by recognising marriage in the tax system - and we'll also end the couple penalty in the tax credits system, which, unbelievably, encourages parents to live apart."