MSHA spokeswoman Amy Louviere told International Longwall News that Stickler’s resignation was effective on Monday, the day of inauguration for new US President Barack Obama.

She said Stickler had his last day in the office on Friday last week.

Louviere did not provide details on a potential replacement, but did note that mining’s federal oversight office would not be without direction for now.

“The president has not yet nominated or identified a candidate for the position of assistant secretary for mine safety and health,” she told ILN.

“In the interim, MSHA is operating without interruption under the leadership of Michael A Davis, deputy assistant secretary for operations, mine safety and health, the senior career official now in charge of the agency.”

Stickler took over as acting assistant secretary in October 2006. His appointment by then-US president George W Bush was met with objection by both Senate Democrats and the nation’s largest industry union, the United Mine Workers of America.

The UMWA did not offer a public statement on the news Thursday.

Stickler was active in the implementation of several new federal regulations, including many outlined for placement by US operations under the MINER Act of 2006. He also took a front-line position with the media following the Crandall Canyon incident in Utah in 2007.