WASHINGTON (Reuters) - The top official of the U.S. National Highway Traffic Safety Administration, who has been key to President Donald Trump’s effort to roll back Obama-era fuel economy rules for vehicles, is expected to leave her position, a person briefed on the matter said on Thursday.

Heidi King, the deputy administrator of the NHTSA, plans to leave the agency in the coming weeks, the person said. The NHTSA, part of the Department of Transportation, oversees auto safety recalls and fuel efficiency regulations.

King’s departure was reported earlier by E&E News. King, who was nominated as the agency’s administrator but has never been confirmed by the U.S. Senate, is not being forced out of her job, the person added.

The Transportation Department declined to comment.

King did not immediately respond to a request for comment, but said in a social media posting: “How do you know when you are working too hard? When your vacation is reported as a career change!”

King was a key person in the Trump administration’s efforts to draft new fuel efficiency rules through 2026. On Friday, the NHTSA and the Environmental Protection Agency submitted the first part of the final regulation to the White House Office of Management and Budget for review.

King said in June that existing fuel efficiency standards have hiked the cost of new vehicles and may “discourage consumers from replacing their older car with a newer car that is safer, cleaner and more fuel efficient.”

The Trump administration said this summer it was issuing final rules to suspend the 2016 Obama administration regulation that more than doubled penalties for automakers failing to meet fuel efficiency requirements.

The final rule, which is expected to be published this fall, is expected to bar California from setting its own vehicle emissions rules.