Government worries over endorsing adoption by same-sex couples mean that children's welfare charities will have to wait until after Easter to try to influence the Adoption and Children Bill.
An amendment on whether unmarried couples should be allowed to adopt was due to be debated by MPs on 20 March but has now been delayed until April.
BAAF Adoption and Fostering, the charity that led lobbying for a relaxation in the law, has not been told why the delay has happened.
The reason seems to be that while the Government is sympathetic to allowing unmarried couples to adopt, it doesn't see a way of doing this without endorsing adoption by same-sex couples.
Last week, BAAF and 18 other child welfare agencies penned a joint letter to all MPs and The Guardian. They argued that the Government's targets for increasing adoption rates by 40 per cent would be impossible to achieve without relaxing the laws for unmarried couples. More than 130 MPs have backed the campaign.