Demonstrators outside the governor's offices on Broad Street in Richmond Friday protest Gov. Ralph Northam's decision to remove two members of the State Air Pollution Control Board as it weighs a crucial permit for the Atlantic Coast Pipeline. (Virginia Pipeline Resisters)

Under fire from environmentalists, Gov. Ralph Northam said earlier this week he wouldn’t seat two new appointees to the State Air Pollution Control Board until after a critical vote next month on a pipeline compressor station.

So what exactly does “seat” mean?

The semantics, it turns out, could be important, because some environmental groups argue that under state law the current members serve until the moment their replacements are sworn in, meaning they could still potentially participate in the meeting barring further action by Northam — an interpretation backed by a 2013 attorney general’s opinion.

And at least one of the members Northam has slated for replacement was holding out hope she’ll still be allowed to vote.

Northam’s administration, however, says it’s planning to go ahead and swear in the new members even if they’re not going to participate in the next meeting.

“They’ve not been sworn in yet, but I expect they will be sworn in shortly,” said Northam’s spokeswoman, Ofirah Yheskel, in an email Thursday. Northam’s announcement that they would not be seated “was a formal way of saying they would not join the upcoming meeting.”

As for the members slated for replacement: “Their service ended when their successors were appointed.”

Northam’s decision to replace the two members — Rebecca Rubin and Samuel Bleicher — after they voiced concerns about a permit for a compressor station for the Atlantic Coast Pipeline has outraged environmental activists, who accused Northam of rigging the vote in favor of the pipeline’s developer, Dominion Energy.

Northam’s administration has called the situation a misunderstanding, saying the governor had intended to replace Rubin and Bleicher after the board’s Nov. 9 meeting, when the vote had initially been scheduled to take place.

When the board members opted to delay action until their Dec. 10 meeting to allow further consideration of testimony and public comment, Northam decided to proceed with his new appointments as planned, Secretary of Natural Resources Matthew J. Strickler told The Washington Post: “If he was trying to get a certain outcome, the governor would have made appointments before this [originally scheduled] vote.”

Northam’s announcement that he would not seat the new board members, first reported by the Richmond Times-Dispatch, led to the some ambiguity regarding the status of Rubin and Bleicher.

Northam told WTOP this week that he never intended the new appointees to vote on the compressor permit.

“I had no expectations from the time I made these appointments that they would be voting. We tried to make that clear. Obviously, it’s a learning curve and they need to catch up to speed,” he said.

Greg Buppert, an attorney with the Southern Environmental Law Center, told The Post that the decision not to seat the new board members meant the old members could still vote.

The stance is backed by a 2013 opinion issued by Attorney General Ken Cuccinelli which concluded that “a member of a state board or commission holds over after the conclusion of his term and may continue to serve in his office and execute the full range of duties of that office until the qualification of his successor.” Attorney General Mark Herring’s office declined to comment, but in an email, Cuccinelli said Buppert’s interpretation is correct.

One of the board members slated for replacement, Rubin, said in a statement there is still time for Northam to correct the situation, arguing she and Bleicher should be allowed to remain on the board.

“I believe that the breach of due process is fully repairable, and that it is well within the power of the commonwealth to allow the regular process to continue such that the terms of Sam Bleicher and I would conclude only after a board vote on the compressor station has occurred,” she said.

Asked whether he was holding out hope he would still be allowed to participate, Bleicher said he was “not willing to comment at this time, as I have not received an answer to the question you are asking.”