Metro General Manager Richard Sarles said Thursday that the transit agency could lose nearly $10 million in revenue through September if federal workers are furloughed because of the mandatory budget cuts set to go into effect Friday.

Sarles, addressing a meeting of Metro’s board, told the directors that on a typical weekday, federal employees account for about 320,000 bus and train trips and about $820,000 in revenue.

Metro has calculated that if those federal workers take 12 furlough days in the next six months, the transit agency would lose almost $10 million.

Sarles said the agency could also be risking at least $12 million in federal funding that’s part of a $150-million-a-year pot of money for capital work, including rebuilding the aging rail system.

“It’s always concerning when you’re losing revenue and you have to provide the same level of service,” Sarles said after the meeting. He said “you can’t juggle the bus or rail service day-to-day,” depending on when federal workers are furloughed, because other riders need to get places.

Sarles said he and his staff are looking at work that will need to be cut if the agency doesn’t receive the $12 million in capital funding from the federal government. He said he will present it to the board this month at its finance committee meeting.

He said he would not “cut safety projects” and would probably spare work on escalators or elevators but work on lighting or signage “could be at risk.”

The prospect of such losses comes as the agency has seen some drops in its rail ridership with increased weekend track work.

Meanwhile, the board also publicly endorsed Sarles and his stewardship of the transit system and its 11,000 employees. Metro Board Chairman Tom Downs said the directors are in talks with Sarles to extend his contract an additional two years.

Sarles signed a three-year contract that expires at the beginning of next year. A former Amtrak and New Jersey Transit official, he joined Metro in 2010 as interim general manager and later accepted an offer to stay on.

The review of his contract comes as two of his top executives are leaving.

On Wednesday, Sarles’s deputy, David Kubicek, who oversees the Metrorail system, said he will resign March 18 after six years at the agency. Metro Transit Police Chief Michael Taborn is leaving at the end of this month.

Kubicek is perhaps best known for helping lead the reconstruction of rail lines and platforms and the opening of the new Silver Line. Kubicek said he was “going to take a little time off” and “evaluate.”