Several gay rights groups and other organizations are asking the State Board of Social Services to delay implementing new regulations they say allow faith-based organizations in Virginia to discriminate in adoptions based on sexual orientation.

The board is required to reopen the comment period if at least 25 people make such a request. It is expected to vote on the decision at its next meeting.

Claire Guthrie Gastanaga, general counsel for Equality Virginia, said at a news conference Tuesday that the group is prepared to sue if the board does not postpone implementation.

Last month, the board voted overwhelmingly to continue to allow the agencies to discriminate after many faith-based groups insisted that they be able to screen prospective parents on religious or moral beliefs.

James Parrish, executive director of Equality Virginia, said the vote was taken at the last minute without a chance for the public to comment on substantial changes recommended days before the meeting.

At the meeting, board chairwoman Bela Sood, who was appointed by former Democratic governors Mark R. Warner and Timothy M. Kaine, requested that the panel postpone the vote, questioning the lack of time for public comment and for the board to consider the latest advice. But the board voted to deny her request.

The regulations, part of a massive overhaul of adoption rules, rejected protections on the basis of sexual orientation, gender, age, religion, political beliefs, disability and family status. The current rules follow federal law banning discrimination based on national origin, race and color.

The board, which has five Democratic appointees, received advice from Attorney General Ken Cuccinelli II (R) and Social Services Commissioner Martin Brown, an appointee of Gov. Robert F. McDonnell’s (R). All three oppose the proposed changes.

“There has already been an extensive, lengthy and easily accessible opportunity for public comment regarding this regulation,’’ McDonnell spokesman Tucker Martin said Tuesday. “Citizen input during that period ran overwhelmingly in favor of keeping Virginia’s adoption regulations in their current, and long-standing, form. The board’s vote to maintain the regulatory status quo was in line with the received public comment. There will already be an additional 30-day public comment period, per standard procedure, after the publication of the final regulation. This organization’s request for another 30-day public comment period will be considered by the board. Public input is an important part of the regulatory process.”

The groups represented at Tuesday’s news conferences were Equality Virginia, the American Civil Liberties Union, Virginia New Majority, the National Black Justice Coalition, Mothers and Others, Virginia NOW, People of Faith for Equality in Virginia and the Family Equality Council.

“The current policy exclude thousands of qualified prospective parents willing to take these children simply because of their sexual orientation,’’ said Jennifer Chrisler, executive director of Family Equality Council.