Heterosexual couples could be allowed to enter civil partnerships, paving the way for cohabiting ­people to get the same legal rights as those who are married.

A private member’s bill setting out the changes, led by Tim Loughton, a Tory MP, is expected to receive government support when it gets its second reading in February.

Loughton, a former children’s minister, said he is “optimistic” of its success. Justine Greening, the education secretary, also signalled her support, telling a recent ­meeting of the Bright Blue think tank: “I am all for equality.”

Supporters of the measure say it would help to stabilise families with unmarried parents, who account for more than half of ­family breakdowns despite making up only a fifth of couples.

Sir Paul Coleridge,