David Cameron accused Labour of "pathological" opposition to supporting marriage as he pledged a Tory government would reward every wedded couple through the tax system.
The Conservative leader launched an attack on Children's Secretary Ed Balls who said the Government planned to tackle family breakdown by promoting any stable relationship, not just marriage.
Mr Cameron told the Daily Mail that a Tory government would "celebrate" and "encourage" wedlock and would change the tax system in favour of married couples.
He said: "Labour's pathological inability to recognise that marriage is a good thing puts them on completely the wrong side of their own dividing line. Ed Balls seems to see marriage as irrelevant. I don't think it is.
"I think marriage is a good institution. I don't need an opinion poll to tell me whether it is or is isn't. That's just what I think."
He said all married couples and those in civil partnerships would qualify for tax relief under Tory plans.
The Department for Children, Schools and Families believes children's welfare can be protected through stable and lasting relationships not just marriage.
Mr Balls told The Guardian: "The Tory policy is that marriage is first class and any other relationship is second class. That is fundamentally not in the interests of children. We should be about supporting strong and stable relationships."
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