The proposed rule could be published in the Federal Register as early as Monday, followed by a 30-day comment period.
After that, the comments will close and it will become final rule .
More than 114,000 cannot be returned to their families and are waiting to be adopted.
The Williams Institute at UCLA School of Law estimated in a report that 114,000 same-sex couples in 2016 were raising children in the United States.
Same-sex couples with children were far more likely than different-sex couples with children to have an adopted child, 21.4 percent versus 3 percent, the report found.