The country's top mine-safety regulator will stay on the job despite the expiration of his temporary appointment as assistant labor secretary for mine safety and health.

President Bush designated Richard Stickler as head of the U.S. Mine Safety and Health Administration on Friday, only a few days after the expiration of his recess appointment. Stickler can only serve for 210 days in the position as the designee, and the White House has renominated him for the permanent position.

The Democratic-controlled Senate has so far refused to approve his nomination. Democratic senators have said Stickler spent too many years as a coal-mining executive and failed to demonstrate that safety is his priority.

Stickler, the government's public face during the Crandall Canyon mine disaster in Utah, took over the $340 million agency in late 2006 as a result of an appointment Bush made while Congress was out of session.

He inherited an understaffed agency that was facing new mandates following the coal industry's deadliest year in more than a decade. Forty-seven coal miners died on the job in 2006, the year he took over the agency.

"MSHA's mission is to help ensure that each and every miner comes home safe after each and every shift, and with Richard's continued leadership and the diligence of everyone at MSHA, miner safety will continue to advance," Labor Secretary Elaine Chao said in a message to MSHA employees.