THE conservative upper house MP Fred Nile has called for the same-sex adoption bill before NSW Parliament to be resubmitted to the lower house, saying the legislation will not succeed if another vote is held.

The bill passed the Legislative Assembly with a two-vote majority, but one MP was in hospital (Kevin Greene) and another (John Aquilina) was overseas. Both would have voted against the bill, Mr Nile said.

''It does raise the question: should this bill be resubmitted? It would then come down to a casting vote by the speaker.'' That would mean the bill would fail, in line with the views of most of the population, he said.

The legislation was also potentially under threat from a foreshadowed amendment by the Attorney-General, John Hatzistergos, which was aimed at limiting an earlier amendment moved by the Environment Minister, Frank Sartor, to give religion-based adoption agencies an exemption from discrimination legislation when assessing adoptions.

Mr Hatzistergos's amendment seeks to limit the exemption narrowly to faith-based groups, arguing the Sartor amendment passed by the assembly was too broad.