Same-sex couples are a step closer to being able to adopt children in Victoria after state Labor voted in favour of changing the law, paving the way for a historic shift if Daniel Andrews wins this year’s election.

Victorian MPs and delegates at Labor's state conference on Saturday unanimously endorsed a platform legalising gay adoption, which would bring Victoria into line with NSW, Western Australia, Tasmania and the ACT.

At present, gay couples in this state can be appointed as foster parents or guardians, but do not have the right to adopt a child together – even if that child has been in their care for years.

Changing the law would fix this anomaly, as well as tackle other inequalities, such as the inability of a step-parent to adopt their partner's child, or the inability of a gay couple to jointly adopt a child conceived through IVF.

Martin Foley, Labor’s spokesman on gay and lesbian issues, said the shift was important step in protecting the rights of parents and their children – ‘‘however they come together".