By David Shepardson

WASHINGTON The White House said on Tuesday that President Joe Biden is withdrawing the nomination of the acting head of the National Highway Traffic Safety Administration (NHTSA) to take the top job on a permanent basis.

The White House gave no reason for the move and declined to comment.

Ann Carlson, the agency's chief counsel, was named acting head of NHTSA in September and formally nominated for the top position in March.

She has overseen safety probes into Tesla Inc, air bag ruptures, efforts to reduce traffic deaths and to boost vehicle fuel economy requirements.

U.S. Transportation Secretary Pete Buttigieg said Carlson would continue to serve at NHTSA but did not address why the nomination was withdrawn.

"Ann’s service has helped advance NHTSA’s mission to save lives and reduce the economic costs of roadway crashes," Buttigieg said in a statement. U.S. traffic deaths jumped 10.5% in 2021 to 42,915, the highest number killed on American roads in a single year since 2005, but fell 0.3% in 2022.

Carlson did not respond to a request for comment.

Her nomination faced strong opposition, with the 13 Republicans on the Senate Commerce Committee earlier this month criticizing her role in the development of fuel-economy standards in 2021. They told Carlson the standards were "consistent with your long career as an environmentalist without traffic safety experience."

NHTSA is set to soon propose new fuel economy standards for 2027 and beyond.

Jonathan Adkins, head of the nonprofit Governors Highway Safety Association representing state and territorial highway safety offices, said the group was deeply disappointed in the withdrawal of Carlson's nomination.

"GHSA urges the Biden Administration to nominate an individual with a strong safety background that can be quickly confirmed," Adkins wrote on Twitter.

Carlson took over NHTSA after Steven Cliff left in September 2022. Cliff was named NHTSA's deputy administrator in February 2021 and ran the agency on an acting basis until he was confirmed in May 2022.

For much of the last six years, NHTSA has been without a Senate-confirmed administrator.

During the Trump administration no nominee was ever confirmed to head NHTSA and there was no nominee for much of the four-year period. The Biden administration has struggled to win approval for many key transportation nominees in a closely divided U.S. Senate.

(Reporting by David Shepardson in Washington; Editing by Chris Reese and Matthew Lewis)